Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
This does not work if just adding a new worksheet to an existing workbook that had the new default setting when the workbook was created. What's the fix for that?
That is correct. As I wrote in the message to which you replied, changing the defaults apply to future workbooks.
In Excel for Windows, you can modify the font of multiple sheets at once if you first group them by Ctrl + clicking the worksheet tabs. Remember to ungroup before you make any additional edits on the workbook.
To send feedback for Microsoft, use Help > Feedback (Word for Windows).