Automatic invisible when on mobile only, or a way to sign out with out logging out.

So I got both the desktop and the mobile app (android native)

For me the majority of the time when I'm on and want to appear online i got the desktop app running.  and when i log off there I don't want to still appear online, as 9 times out of 10 I won't be looking at the mobile app. but it's a pain to have to manually set status every time or to have to fully sign out and then type in everything to log in on the mobile app the few times I do use it. 

so I'd like some option where I can either set it so that when I log out of everything other than the mobile app it auto sets me to invis. so when I'm not wanting to use the mobile app, the status indicator is updated properly. and then the few times i want to be shown as on line via the app I can switch it on manually. 

or have an option so I can partially log out of the mobile app.  so like the app acts like it's fully offline but it still saves my credentials so when i want to sign in I don't have to re-enter everything, I can just hit a log in button.   That way the 9 out of 10 times I don't want to use the mobile app I can appear offline since I effectively am. but don't have to bother with the hassle of having to resign into the app those few times I do want to use it.