suddenly, I am getting a different font in Firefox

it's like a typewriter font

I like it much more than the regular sans serif font I get

but I think sans fonts are theoretically easier to read on screens... so maybe this change was not intentional

@Zanna On all sites?

yes

everywhere

In 19.10?

everywhere in firefox in 19.10. Not in other programs

Sorry, that question was unclear.

that's ok, but have I failed to answer it?

it looks so nice

I am actually having a lot of weird behaviour

like sometimes the desktop background settings get wiped

when it happens, I get a message when I end the session saying "are you sure you want to log out? All changes made will be lost" as if the system is read only

I haven't actually tested whether it is read only though

@Zanna No. You answered it. I was just wondering what OS and release you're running Firefox on.

but, after that happens, the settings don't come back

That is very strange.

even though I can save my work and don't get that message any more

in subsequent sessions

also, the touchpad will slow down. I mean the mouse cursor speed

I make it as fast as possible

Is this computer new?

If so, perhaps the underlying problems is defective hardware.

sometimes it will just slow down to default

yes it's new

@EliahKagan it could be yes

You could possibly test this by making a new user account and using that.

If the problem goes away, it was probably not due to a hardware defect, and probably is something in the files in your home directory.

I always make an extra sudo user in case I mess up

but looks like I haven't actually done that yet :)

also I haven't really changed any settings

I don't think you would necessarily have to made any deliberate changes for something to go wrong in your settings.

You might want to check and see if any files in your home directory have unexpected ownership or permissions.

You might try running:

find ~ ! -writable