The unit will do it's best to detect the resolution and size of any external monitor/TV however sometimes it may need a little tweaking. First make sure the resolution of the display is set to auto if the option exists (for external TVs and monitors). You may want to try different aspect ratios as well. If that doesn't work, you can manually adjust this if you have a USB keyboard. The instructions are as follows:
With a USB keyboard plugged in:
- Press the Option key (could be a windows logo, or Alt key depending on keyboard). This should bring up a menu in the upper left of the screen.
- Use the arrow keys to go down to "Accessories", then arrow right, and down to "Terminal" and press the Enter key. This should bring up a black terminal window.
- Enter the following command: sudo nano /boot/config.txt then press enter. This will open up a file.
- Use your keyboard arrows and find the line that says disabled_overscan=1 and change it to disable_overscan=0
- Now, at the bottom of the file add the following:
- If you’re only seeing issues with the top of your screen for example, only add the line that says overscan_top. The values (50 in this example) will need to be tweaked specifically for your display. The higher the number, the more space will be added at the edge of the screen.
- Then press ctrl o then enter and then ctrl x then enter (this will save and quit out of the file)
- Lastly, type sudo reboot, and press enter. This will restart the display.
Unfortunately this is a guessing game and you’ll need to save and quit the file and restart for the settings to take effect. When it restarts, if it still doesn’t look correct, follow the instructions above and change the overscan values for any/all edges of the screen that are having issues.