"Check for new beta releases" checkbox grayed out

Apologies if this question has already been addressed—I did search for a solution, cleared the cache, and tried other troubleshooting steps, but nothing has worked so far.

I’m quite frustrated with the frequent update popups in DO. I would like to switch to only updating main distributions; however, the checkbox for "Check for new beta releases" under Settings > Preferences > Internet Updates is grayed out, and I can’t uncheck it.

Does anyone know how I can resolve this issue?

Thank you in advance for your help!

Install a release.

Thank you! That solution worked perfectly. I hope you don't mind me saying this, but I wouldn't describe the solution as entirely self-explanatory.

I guess that's why hitting F1 takes you from the preferences to the docs: