I was looking here to figure out why my Personal Macros workbook was opening as "Read-Only" in Excel for Mac (v16.61), but couldn't find the answer. I finally figured out the reason, and the solution, on my own. I think what happened is that when Excel crashed previously, and I reopened it, this workbook opened in Auto-Save. (which is Read-Only). I searched my Mac for what I thought was the original file (located in the ~/Library/Application Support/Microsoft/Office/Excel folder, which is where it resided in a previous incarnation of Excel), and saved it over that file).
The solution was to find the correct folder location for this special workbook (as indicated in the Help page accessed from Excel's Help menu, "Create and save all your macros in a single workbook", which describes the path as ~/Library/Group Containers > xyz.Office (where xyz be a text string, like "UBF8T346G9") > User Content > Startup > Excel. I moved the Personal Macros workbook into that folder, and quit Excel. On restarting Excel, it opened normally (not as Read-Only). Hopefully this may be useful to someone else.
