Why aren't all Sales Order records displaying for a certain user?

From the User Setup window, you can restrict or grant access for non-administrative users to certain SO Types.

To do this, go to (Admin > User Setup). In the User Setup window, highlight the DBA user name you wish to change the permissions for, then go into the SO/Job Types tab. In the SO/Job Types tab, you will need to check or un-check the SO Type you wish to grant access to or restrict access of based on the DBA user you have highlighted in the main User Setup list screen.

After you have made these changes, the user should be able to see the Sales Order Types they have access granted to. You may need to restart the software for this change to occur.