Time Level greyed out in Timeline Slicer when Excel sheet is protected

[DaveT]

Apogies if this is the wrong forum, I am a newbie. 

I have built a dashboard in Excel 2016 and have the Timeline slicer unlocked (and when I protect the worksheet in Excel the user can change the dates in the timeline slicer) but, when I protect the Excel sheet the Time Levels are greyed out.

I have looked on forums and can't find this issue raised/answered anywhere and I cannot find a setting in Excel that would enable me to unlock the Time Level in the Timeline slicer.

Am I missing something, or is this a known feature/issue when protecting sheet in Excel 2016?

The problem is that I have to set the Time Level to months for most analysis, but the users then want to view by Quarters so I have to unprotect the sheet each time.

Thanks

[v-sihou-msft]

@DaveT

This issue is more related to Excel. Please post your question on Excel forum: 

https://social.technet.microsoft.com/Forums/office/en-US/home?forum=excel

Regards,