I've connected my Raspberry Pi 3 to a 7 inch display touchscreen through an HDMI cable. The problem is the display's aspect ratio doesn't match that of the screen, so there's a black bar on the right about an inch and a half wide. Moreover, if I touch the middle of the screen, it registers the touch in the middle of the display, which is slightly to the left of the touch.
I've googled this to try to solve it and they pointed me to a file called
/boot/config.txt, which contains overscan settings. I tried setting overscan_right to -20, and when there was no noticeable difference, I tried the extreme value of -100000 (every source said negatives were for expanding display and positives for contracting). I tried setting overscan_left instead. I tried both possible values of disable_overscan, making sure to run
sudo reboot after each change. Nothing has even made a noticeable difference.
Is there something that I'm missing? How do I get the display to fill the entire screen?