If you want to see the list of projects a staff has been assigned to, you can use the People Explorer Report:
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1. Go to Reports > Explorer

2. Select the Date Range - you can set the start date to as far back as you want

4. Type the name of the person in the search bar, next to the Filter button

5. Click the mini arrow to the left of the person's name - then you should see the list of projects they were assigned to during the specified period