"I want to have timestamps in my workbook showing who/when the workbook was last edited. That would be a separate date/timestamp for any user who uses the workbook."
Any number of users
Should add users automatically
Each user's date/timestamp only gets added/updated when a change is made in the workbook, not just from viewing it.
A separate sheet called LOG must exist in the workbook. The macro does the rest.
The macro below goes into the ThisWorkbook module and watches for activity anywhere in the workbook except the Log sheet.
If an edit is detected, the users Windows Login name is detected and updated/added on the Log sheet.
Nothing says "thanks" like a steak dinner!