(Thanks to passthroughpo.st and urcomputertechnics.com for the tips.)
- In the macOS Finder, look for EFI in the left bar under Volumes. If it isn't visible you will have to mount it:
- Open the macOS Terminal and type
diskutil listand look for the disk/partition location of the EFI. (There may be more than one.) - Type
sudo diskutil mount diskYsZ, using the disk/partition location name where you see EFI. - The EFI partition will appear in the left Finder bar under Volumes.
- If you don't see anything in that volume after browsing to it, try the other ones that you found in
diskutil.
- In the EFI volume, go into the
Cloverdirectory and open theconfig.plistfile in the macOS text editor. - There should be a section of the file that looks like this:
<key>ScreenResolution</key>
<string>1280x720</string>
- Edit that to your preferred screen resolution.
- Some odd/intermediate resolutions like 1366×768 may not work well. Try to stick to more common 16:9, 16:10, and 4:3 form factors.