title: Google Spreadsheet replacing a value by another value upon edit by user
body: <p>I have just started to find out about Google Spreadsheet Scripts, but I can't figure out how I go about doing this:</p>
  
  <p>I am looking for a script that replaces just one specific cell content value ("icecream") for another value ("donut") upon editting/adding. </p>
  
  <p>So far I have found this piece of script on Stackoverflow, but this only works on a cell (not the value in the cell ie. "icecream").</p>
  
  <p>And it only works on me clicking play (I want it to do it automatically, everytime a user enters the specific value into a box. So, if a user enters "icecream" into a cell, it needs to automatically be replaced with "donut"). It doesn't matter which cell the value "icecream" is in, just change the word "icecream" to "donut" automatically for the entire document, everytime someone types in the word "icecream". </p>
  
  <p>Can someone help me?</p>
  
  <pre><code>function doTest() {
  SpreadsheetApp.getActiveSheet().getRange('E3').setValue('donut');
  }
  </code></pre>