How do I restrict some members to view only excel files within teams, and others to edit?

Hi yossi2001 

This is slightly complicated but bear with me.  If you have Team members but you want to split that into 2 groups Team Members A and Team Members B and assign edit to one and view to the other, it is doable.

The way I think you could do it is change the permissions on the document to view for all Team members - as per Chris's walkthrough. Then create a SharePoint permissions group called "Excel Edit" or similar and add that into the excel file that you want to be editable  and give edit permissions to that group.  Lastly add the users into the "Excel Edit" SharePoint group  that you want to be able to edit the file.

You will then need to manually update "Excel Edit" as and when there are changes to the users that you want to be able to edit files.