I've recently moved my GOG games to a new drive, but the offline installers keep defaulting to the old drive, no matter how many times I install games to the new one. Anyone know how to change them to default to the new drive?

You sure, that you use the offline installers?

Thanks, that seems to have done it!

The key things (both unpopular nowadays) is:
Don’t keep everything installed, it’s messy, creates issues, and takes up far more space than needed and you will not play everything anyways. Just install what you need. Offline installers are far simpler to use and store.
Don’t “move” things, it has the potential to break various things, and can cause issues that are next to impossible to debug especially if you mod anything. As above, offline installers as smaller so easy to store and install fresh when needed.