You have a 1080p or 4K TV but 720p Output? X7, Q7, V9, X8-U
If you're certain that
a) Your DroidBOX® device is capable of outputting 1080p or 4K (UltraHD) and
b) That your TV is similarly capable, then please...
Open the list of all installed Android applications, locate the Settings icon and click on it (if you find you have a small window displayed instead of something like the screenshot below, please select the last tab and click the More or Advanced Settings button), you should see one or two sub-menus that refer to Screen and/or Display.
One of these may have an entry that relates to resolution. Most likely the options (when you click on it) refer to 1280x720p 60Hz, 1280x720p 50Hz, 1920x1080p 60Hz and 1920x1080p 50Hz (also some SD resolutions may be possible).
Should your device currently be set to either of the 720p modes, please select 1920x1080p 50Hz. If you don't see these entries anywhere, your device is currently outputting the only video mode it can.
If at any point the display on your TV stays blank (you'll probably notice a momentary pause whilst switching resolutions), do not panic, simply press NOTHING on your remote control and Android will interpret this as a reason to revert to the previous resolution. If this lack of output does occur, try the 60Hz option for 1080p. Should you find that Android itself is already set to 1080p, please leave it on this setting.
Next we'll check XBMC itself. To do so, please start XBMC. Underneath the System entry, you'll see Settings, please click it. Now select System then Video Output and check what the resolution is set to.
If 1280x720 (or 1280x672 if you have the Android bar at the bottom visible), click the little arrows next to it until 1920x1080 (or 1920x1008) is selected. You'll be asked if you want to keep this resolution - assuming your TV is displaying XBMC, confirm your selection. Again, if there is no option for 1080p, then your device is not capable of 1080p.