I absolutely cannot stand this behavior, if I accidentally tap instead of scroll then comment trees will expand/collapse and then I feel lost. Jerboa has this behavior and it was the most annoying thing about it when I used it, I'd say it was close to making me feel nauseous at times.
But hey, that's the great thing about Sync being so customizable, you can choose whatever behavior you prefer!
On your Lemmy account settings when logged into your home instance from the web, do you have "Show Read Posts" unchecked? That will insure any posts you've marked are read from any client won't get sent to you again when you refresh your feed later. This is a double edge sword as it can make finding read posts harder when uncheck. Some clients may do some filtering on the client side, but also enabling this server side make hiding read posts a lot more consistent between browser and other clients from the same account.
That's it! Thank you, this works, but I have not found option to enable that by default... Edit: actually that's just hides read... On app reopening they are back...
Only problem I have with it is I can't quickly turn down the sound when I have a comment thread up. My solve for that is usually to quick pull down the notification bar, then the volume keys work for volume again until the notification bar is dismissed.
hmm. the collapse parent setting isn't working for me for some reason. it's on but the parent comments aren't collapsing. dunno what's going wrong on my end ¯\_(ツ)_/¯