How to globally edit group banner?

Hi there, I know I can go into a group; then Admin > manage group theme > edit this page > click on "edit header" > mouse over Group Banner widget > click the gear to configure the widget > Add navigation item > under link type, select Group Calendar(s) and give it a name > save.

Question: Is there a process that I could do this for all group banner widgets at once (globally)?

And if so, would it reset any differences in the group banner between groups to a standard configuration based on the global edit? Or only change what I changed?

Thanks in advance! (we're on 10.1.5)