Comic panels being too small to read?

[JimPhelps]

So I haven't been able to figure this out. I've been making my own comics out of jpgs into Calibre, I get them converted, the files stay colorized, but when I put them on my phone to use in my ereader app (Media365 Android) the pages of the comic are very small. I mean, I can't get them to expand to fill the available space. I know this app isn't really intended for comics since there is no pinch and zoom option like Kindles, etc. but am I wrong for thinking there is an option when converting my cbr file in Calibre that can help me get the files to stretch to the size of the screen in this app?

I've looked under the Page setup in Converting books, and best i can set is a Default profile.

Under Comic input, i've checked Keep aspect ratio when converting and its still only about 30-40% of the screen filled when i open the book on my phone.

Is there another setting I should adjust so these comic files can take up more of the screen since there is no Zoom option on this ereader app(Media365 universal book reader)?