I think TheVCBK is talking about no. 1, the keyb setting in dosbox.conf.
Now, I understand that the UI isn’t meant to include every single config option. But come to think of it: would it be possible to simplify the export-to-clipboard-then-paste-to-expert-settings workaround?
Like, adding a button “Copy config to Expert settings”, that will automate this process? Of course, that would also require an “Are you sure?” yes/no confirmation dialogue, to avoid accidental deletion of user tweaks in Expert settings. ?