[Shirazmn]

Got it I think

I remember that some templates had troubles uploading files. I use the Classic Blue and it works from both mobile and PC, but it doesn't have a mobile friendly interface (I prefer it this way, tbh).
To change template you can go to your User CP (control panel), Edit Options (from the menu), and you should find "Board style" towards the bottom . Classic Blue works, some other don't.