I've tried to look it up on the app and online, but I couldn't find a way to set the mat mode for the pictures I batch uploaded from the USB drive. And it always set the default ugly mat that doesn't blend in to the environment at all. The ugly mat really takes away from the "real picture frame" experience.  

The only way I to work around this is to first select each individual art work and customize the mat. It is extremely tedious if I have 100+ art work upload each time... (Even worse, after I select each art work, customize the mat and go back. It jumps back to the beginning of my album... It is really hard to track which art work I have set the frame and which I haven't)

It'll be great if there was an option to set the default mat for all pictures in the app's settings!