Excel PivotTable Output Data

I can create a simple table, say one column labeled Numbers and enter 1-12 below it.  I create a PivotTable from this and everything works as expected.  The PivotTable mimics the table.  

Here is the problem: When you click a cell in the PivotTable my assumption was that I cannot change the data.  A matter of fact, if you push the 'Delete' key it says you cannot because this is a PivotTable.  However, if I click the cell in the PivotTable output source I can delete the value and type whatever I want, and it stays.  I can still change the source data and the PivotTable updates with this information, but the cell I changed stays.  

Why can I change the output data?  

My Solution: I found I can protect the sheet by checking all box under 'Allow all users of this worksheet to:', but leave 'Use PivotTable & PivotChart' unchecked.  When I unprotect the workbook I finally get a message that says "We can't change this part of the PivotTable."  Really?? This is the solution to prevent users from changing output data?  

Please confirm!

Jason