Users can access the modules based on their permission. 

Admin: has unrestricted access to all the modules. You as an admin, can assign permission for role.

Update Permission 

• Step 1. First, you create roles at Settings -> Access Permission -> Roles
• Step 2. Next, go to Settings -> Access Permission -> User Roles: assign roles to employees
• Step 3. Go to Settings menu under Purchase module from the left sidebar -> Select Permissions menu -> Select a role -> select the necessary permission
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• Step 4. Click Save button