Hello, I am not sure how or when it disappeared, but I was not able to make this gear icon to reappear.
What version of RStudio are you using? This was a bug when switching to the visual editor mode and back that was fixed in version 1.4.1035.
I am using the following version:
When I switch to the visual editor mode, the icon shows up. But when I switch back, the icon disappears again.
This does not happen on my two Macs, both with MacOS Monterey 12.1, R 4.1.2 and RStudio 2022.02.0+391. One has an Intel cpu and the other the Apple M1 pro. I also reverted the latter to RStudio 2021.9.2+382. Sorry for the false lead on your issue.
Thank you for your reply and sharing the information. I also uninstalled RStudio and reinstalled it, but still the icon is missing.