How do I do it? I don't want to download any other programs for it, I just want to find a way to edit a few keybinds.

I found an old post by myself from a few years ago where I apparently was able to do it by opening "Launch Settings" in the game folder, but after redownloading the game I can't find it :p

Ok, I figured it out. If you open Setup.exe (I had to drag and drop it onto DOSbox.exe to get it to open), you can rebind the keys that way

To give a quick update, using GOG Galaxy you´ll find these settings by clicking the "slider button" next to the Play button -> additional executables -> sound settings