ZTE Blade X Max

I just bought a ZTE Blade Max about a week ago, to replace my Samsung. One thing I've noticed, for being a "media replacement," it has trouble on YouTube. It keeps buffering after about a minute of play, then it looses the screen. I have sound, but nothing on the screen. I have to exit, then reload, the app to get the picture back. I tried adjusting the settings to "auto" in the app, but it still does it. I have Uverse as my ISP. Any suggestions?