title: getActiveSpreadsheet().getActiveSheet().getName() not updating with new sheet name
body: <p>I'm trying to create a generic timesheet for my school project. I created a simple function to get the name of the active sheet.</p>
  
  <pre><code>function SetSheetName() {
   var Sheet = SpreadsheetApp.getActiveSpreadsheet().getActiveSheet();
  
    return Sheet.getName();
  }
  </code></pre>
  
  <p>It works just fine the first time I use it. But if I change the name of the sheet and re-call the function, it stills fetch the old name of the sheet. </p>
  
  <p>For example, if the name of the sheet was "Sheet1" and I run the function in a cell, the cell value will be Sheet1. But if I change the name of the same sheet and re-call the function, I will still get Sheet1 no matter what. </p>
  
  <p>I guess it's the way google docs functions, but I am not aware how to fix that problem. </p>