BUG FOUND (NOT a serious bug)

[Falloutboy]

When changing the output directory for whatever you are doing under the preferences the changes do not take effect until you exit MakeMKV and restart it - it makes no difference if you press the apply button either.

[Yugatha]

It normally doesn't take effect until you read a new disc. If you want to change it one-off, or a different directory for each disc, consider using Expert mode - it allows you to override the output directory.