The Sims 4 custom graphics settings don't stay

@protokirbyblaze  Settings are stored in options.ini, inside Documents > Electronic Arts > The Sims 4.  If the settings revert every time, the issue might be your antivirus blocking changes to the contents of the Sims 4 folder.  But it doesn't sound like that's exactly the issue here.

Since the settings only revert some of the time, that suggests one of two causes.  The first is that you've set Nvidia's GeForce Experience, or perhaps an equivalent option within AMD or Intel software, to "optimize" your game settings.  Disable this, and the application should no longer interfere.  The other is that OneDrive is syncing your files and periodically replacing your local options.ini with one saved to the cloud.

In that case, get rid of the current cloud copy.  First, pause syncing, which you can do by right-clicking the OneDrive (cloud) icon in the lower-right corner of the screen.  Make sure your in-game settings are currently exactly the way you want them.  Sign into onedrive.com, and delete any options.ini you find in My Files.  Then when you resume syncing, OneDrive should upload your current options.ini, so even if it syncs again, it'll be syncing a version of the file with your preferred settings already in place.

Sorry for the heavily late reply. My onedrive doesn't have any options.ini and as for the other stuff, I have never once signed up into the GeForce thing on my computer but do I have to make an account on that in order to change settings or would the settings not even be there without an account? - meaning there's some kind of different problem?

@protokirbyblaze  The option to "optimize" game settings is a feature of GeForce Experience: you'd need to have installed it and checked the box to enable the option.  I don't know another reason why your in-game settings would revert like that.  It's possible that the options.ini file is corrupt, so you could try deleting it and see if the new copy the game creates works better.

Please also check your antivirus, if you use a third-party program, for any recent actions involving Sims 4.  If so, that's the issue, and you'll just need to set exceptions for TS4_x64.exe and EADesktop.exe.