can find support for this app

I’ve been using this app for months worked great until one day I played video but it won’t fill the whole screen. everytime I plays video there are black gap on the bottom, left and right sides of my screen. I’ve been trying to find a way to make it back normal but I dont know how to do it. tried to go to the support page butt all in chinese which is no good. tried google for solution but still can’t find any.
IF ANYONE KNOW HOW TO FIX THIS PLEASE LET ME KNOW !!! Thanks

Ghoz162 about SPlayer - Simple and Powerful