Can one staff member update another staff member's timesheet?

Yes

To do this, you should have permission lists activated for Glide Time. This will mean that access to all Glide Time data is controlled by highly configurable permissions lists.

To activate permission lists for Glide Time, please follow the steps at the bottom of this article: https://glide.helpscoutdocs.com/article/285-configure-permissions-lists-for-glide-time

You should then add the user that you want to be able to edit timesheets, or a team that the user is in, to the following permissions lists:

• Can Submit/Un-Submit Other Users' Timesheets, and

• Can Access Timesheets Report.