First you need to create groups from Settings. Please read this article to know more: What is a Group and how do I add a Group?
1
Navigate to Screen module
Navigate to Screen module.

2
Open screen and scroll to Groups section
Open the screen for which group needs to be added, by clicking on screen name and scroll down to the Groups section towards the bottom.

3
Click on Add Group
Click on Add Group.

4
Search and select group
Search and select the group/store you want to use and click on Assign.
It will look like below:

