I'm using a browser called Puffin Browser, bit this is essentially for every browser I ever use.
I usually just have one tab on the very front for my dashboard and the second tab as the forum.
If you did not log out and deleting the tab you've opened and closed the browser by simply closed by force closing it (I don't really know what to say it) and not closing it directly from the app, you will just be able to get to the forum tab anytime you open it. BTW, keep in mind to let the browser save the password when you log in to the forum and tapas.io. it'll save you time and you won't have to log in every time except tomes when the browser go error...
Also, there's no need to open desktop mode on the forum. You still need to open the desktop mode on tapas.io but once you stay on your dashboard, that is unnecessary anymore.