Hi
I only play video on my iPhone/iPad a couple of times a year but I do however play music from them fairly often. It would be nice if I could tell the app to automatically open my music library whenever the app starts.
I know I know, talk about a first world problem, but still. It would be a nice feature I think many would appreciate.
naving plex open to a specific library is what a lot would like to have, as well as a customizable ondeck section.
You didn’t mention which app you’re using, but on Plex Web you can bookmark the library you want to start on. Other apps would require some work.
At least we agree on this 
The official for ios.
If using iOS that feature exists. Navigate to the Hamburger Menu top left and select the Library to default on opening. Also you will need to at least once select Library from bottom menu so it remembers or it will still open at recommended.
