Users in Nexonia can be filtered so that they can only see and select Project values that a Nexonia Administrator allows them to.
To enable filtering of projects by user, please navigate to: Settings > Company > Features > Edit.
Scroll down the page until you reach the Internal Contacts section. Then check Sub-Selected At Project Level.
Next, navigate to: Setup > Users > Users > click on the Edit icon next to the desired user > Projects > Edit.
Check the Projects that the user should have access to and click Apply at the bottom to save.