SharePoint: How to change member access for a secure document library
Follow these steps to change member access for a secure document library.
Step 1: Access your document library. Select the gear icon in the upper right-hand corner.
Step 2: Select Library Settings.
Step 3: Select Permissions for this document library.
Step 4: Select Stop Inheriting Permissions.
Step 5: Select the user group whose settings you want to adjust. Select Edit User Permissions.
Step 6: Adjust the settings. Select OK.