Owner Restriction

To restricting user based on Owner (creator of record),  form/document should have field linked with User master. If that document is not linked with user, then you should create custom field and link it with User master.

Following are the steps to restrict User based on Owner.

Step 1: Go to:

Setup > Permissions > Role Permissions Manager

Step 2: Select Document Type for which you want to set user permission. After permissions are loaded for selected document, scroll to role for which you want to set restriction.
 

Step 3: For Role to be resricted (Sales User in this case), check "Apply User Restriction". On checking Apply User Permission, two links will be show up called:

- Select Document Type
- Select User Permissions

Click on "Select Document Type".



Step 4: Check mark on User, and un-check for others. If you want user to be restricted based on some other criteria as well, like territory, customer groups, then that should be checked as well.

 
When restricting User based on User master itself, then there is no need to create User Permission Setting.