It's been a long time since I watched YouTube videos that are based on things I actually like, due to depression.
I got news that I'll be heading back to work on Monday night, making things a bit better for me, so watching videos from
the YouTubers I'm subscribed to is a must. Great YouTube content...
... and even though I'm making plans on purchasing another laptop soon, my Lenovo IdeaPad 100 keeps changing the time back three hours behind,
when I'm done watching a video, or sometimes after every two videos.
Can someone please tell me... why? And this isn't the first time this has happened. What is up?

Does the laptop have internet access and is turned on the rest of the time ?

I think what happens is, when you watch videos you are connected for long periods, in which the OS happens to successfully sync the clock to an NTP server online (a server that responds to "whats the time now ?" requests). In addition your time zone settings dont match the time zone you really are in, so it syncs to the wrong time zone for you

It's been a long time since I watched YouTube videos that are based on things I actually like, due to depression.
I got news that I'll be heading back to work on Monday night, making things a bit better for me, so watching videos from
the YouTubers I'm subscribed to is a must. Great YouTube content...
... and even though I'm making plans on purchasing another laptop soon, my Lenovo IdeaPad 100 keeps changing the time back three hours behind,
when I'm done watching a video, or sometimes after every two videos.
Can someone please tell me... why? And this isn't the first time this has happened. What is up?

Which operating system?

I find newer Windows releases to get this bug quite often. I have a dual-boot Windows 8/Linux machine.
When booted into Linux, time is always correct.

When booted into Windows 8, time is WAY off, I wanna say 8 hours. I can go in and change it, it'll be fine for a while then changes again. I have tried everything the interwebs have suggested will correct it, no luck. I have found several paths in Windows 8 to change time, no luck.

Have I ever mentioned I hate Windows? My computer is booted into Linux 99.9% of the time!

Mind you that by default most Linux systems expect the BIOS clock to be UTC (and calculate the shift for the local time in the OS), but Windows expects it to be your local time

Mind you that by default most Linux systems expect the BIOS clock to be UTC (and calculate the shift for the local time in the OS), but Windows expects it to be your local time

The thing I noticed about W8, there are many seemingly different ways to set time. Technically, you just select your time zone and sync with Windows server. That is what my W8 is configured for, and will be correct immediately after I apply that setting. However, after a short time, my PC will be off by about 8 hours.
If I go check the settings, it's still "correct", Pacific Standard time and windows server.
Previously, this used to be a red flag for a virus.
I think W8 is such garbage that's just the way it is.

Right now I've got Windows 10... however, a couple months ago Windows tried to "upgrade" me to the newest version of Windows 10.
THAT'S when I started having issues with the time especially. Then there were keyboard changes. I forgot some of what changed, because
almost everything went back to normal when I switched back over to the older version of Windows 10. Another thing that happened -- my computer
would start up very slowly and sleep slowly, after the upgraded Windows 10, while loading new "intro images." (Is that what they're called?)
When switched back, everything went back to normal.
The main issues I have now because of the stupid "upgrade"... I have to press the FN key in order to operate
the "F" keys successfully... and time goes way off while I'm watching YouTube videos.
Here's an additional issue: starting earlier today, sometimes when I start up the laptop, it fails to connect to the internet,
and runs very slowly. I then put it in sleep mode and it takes about 5 minutes to finally shut down. Then when I start it back up,
everything is back to normal speed. Bruh.
It's time for a new computer... if I can just save the money between now and the next paycheck before this computer permanently fails,
I'll be all good.

Windows 10? Time for new computer already?

Ah, OK. Let's give Bill Gates more of our money so ha can be #1 contributor to WHO!

I've had this computer/windows 10 since late 2015 lol... and I've had problems from time to time even back then.
But... this computer has run it's course. I have to get another one. It will be Windows again unfortunately.
(Sorry to the Windows fans out there, but I am NOT a fan of Windows compared to Mac.) The computer (or laptop)
that I purchase afterwards, WILL be a Mac.
Ok so a couple minutes ago, something new happened. I noticed that my laptop fans were running really high.
"Uh oh," I said. "Task Manager time it is!" I went to Task Manager and noticed "Windows Module Installer Worker,"
with a really high MB. Disk percentage was at 99% at this point. I dug in further and noticed TiWorker.exe. I don't
know if it has anything to do with windows trying to upgrade me again, but I ended the task, and everything went...
right back to normal. Hmmm...
For the record, I HATE ending tasks I don't know about, because I never know what'll happen afterwards.

Brain explosion.

New install time - Nothing here looks like reason for a new computer. At most check the hard drive and whether any heatsinks are clogged...

Although, the laptops from the last 7 years or so are not impressive in their durability to say this lightly, and the newer/slicker they are the more they are fit for the WEEE bin straight out of the packaging

@Ash, nope in my case I definitely need a new computer. If there is any unexpected component failures within the computer,
I lose important files. I want to be able to duplicate files from this computer to another... just in case. Then maybe continue
to run this computer to the ground afterwards. After that the third computer will be a Mac, so that I get both worlds. Mac and windows.
In my case, I know nothing about the internals of computers or laptops. I refuse to take my laptop to any computer technicians.
And it's not to say that I trust the newer computers though, from either Windows or Macs... because I really, really don't.
The slicker they are, the more I typically don't trust it. But the more laptops I have, the more instant back ups in case one fails.
Not just for files, but also internet in general lol

If you are concerned about losing important files, try a backup or cloud service.

Buy an external HDD and copy all your information to it on a regular basis.

I use an external solid state HD and mirror that to the cloud.

I've had this computer/windows 10 since late 2015 lol... and I've had problems from time to time even back then.
But... this computer has run it's course. I have to get another one. It will be Windows again unfortunately.
(Sorry to the Windows fans out there, but I am NOT a fan of Windows compared to Mac.) The computer (or laptop)
that I purchase afterwards, WILL be a Mac.
Ok so a couple minutes ago, something new happened. I noticed that my laptop fans were running really high.
"Uh oh," I said. "Task Manager time it is!" I went to Task Manager and noticed "Windows Module Installer Worker,"
with a really high MB. Disk percentage was at 99% at this point. I dug in further and noticed TiWorker.exe. I don't
know if it has anything to do with windows trying to upgrade me again, but I ended the task, and everything went...
right back to normal. Hmmm...
For the record, I HATE ending tasks I don't know about, because I never know what'll happen afterwards.

Brain explosion.

2015? You can still use it.
According to Microsoft "forum", TiWorker is related to Windows update, seems to be an optimizer which requires some time to run.
Which version of windows do you have? I have upgraded a lot of pc to 1909 via windows image creator tool.
If you have an HDD, random read and writes will kill it performances, so it is normal to have an slow pc during updates.
However, if it takes 5 minutes to shut down, there are some processes which are locking your pc (windows update, anti virus, some drivers, some software).
Try:
1) Upgrade to build 1909.
2) Disable all non Microsoft services (msconfig)
3) Run a SMART check of your hard drive (Crystal Disk Info, it is free)
4) Check power performance settings in your control panel.

How much ram do you have? Lesser the ram, grater will be disk usage due swap file.

I use an external solid state HD and mirror that to the cloud.

I recommends mechanical HDD over SSD as a backup device, because SSD, being a flash memory based drive, have a limited write lifetime, and backup consists of mainly writing. Eventually after lots of backups, the SSD will loss its speed and performance and causing writes problems.