Welcome! This forum has a treasure trove of great info – Scouters helping Scouters! Just a heads up, though - all content, information, and opinions shared on this forum are those of the author, not the BSA.
We don’t use Scoutbook except for the required Internet Advancement function. I just logged in to do an advancement report and ran into an issue that I have not had before. My position is listed as “Lion Adult Partner” which I am, but I am also Cubmaster. Since SB things I am an AP, it wont let me approve any advancement.
Go into My Account → My Positions and check that Cubmaster is marked as your “default” profile position (it should have a little gray head and shoulders icon next to it). If it isn’t, click on the Cubmaster position and in Default Position turn the slider on (so it turns red) and then scroll down and click Update.
If both Cubmaster and Lion Adult Partner are already marked as default positions, go into the Lion Adult Partner position and turn off the Default Position slider (so it turns gray).
AFAIK, this must be done in Scoutbook (scoutbook.com) rather than in IA2 (scoutbook.scouting.org). I wasn’t clear if you were using Scoutbook or IA2 from your original post.
You can go into Scoutbook to make that change. It’s the issue of tracking advancement in both Scoutbook and IA2 that causes most problems between the two.