On an individual donation: 
  1. Go to Sales > Order Search.
  2. Search for the online order and open it.
  3. Go to the Documentation tab.
  4. The note is listed here.
To see all online order comments:
  1. Navigate to Analysis, then click on Information Library
  2. Click Add an ad-hoc query.
  3. Select the Source View of Sales Order and click OK.
  4. From the middle column, drag Sales Method type into Include records where. Set Equal to Online Sales.
  5. In the left column, select Notes. From the middle column, drag Notes to Include records where. Set equal to Not Blank.
  6. From the middle column, drag Notes to Results fields to display.
  7. Click the Set Save Options tab and Name the query
  8. Save and Close