Hi there Lara, I was on my Samsung phone reading posts and the browser was Chrome.
The phone reverted from desk top to mobile and back to desktop, then back again to mobile, where it stayed. I was however, able to reset it back to desktop.
Despite being a mobile device, I prefer the desktop site, which is what it was originally set to.
It appears to be fine now.
Last night I was on my old Google Pixel C and it happened once, using Chrome again, as my browser. Something strange happened. A recently deleted thread (Saving drafts) popped up at the top of The threads I'm on list, then disappeared within seconds.
I have absolutely no problems on my PC, where it has remained on desktop.
Hope this info helps, but will probably confuse things even further!
Sorry I'm a bit of a geek, problems like this intrigue me!