If the fund was automatically linked, you will need to download the transaction into a batch within The Raiser's Edge and then manually adjust the fund within The Raiser's Edge. 

If the fund was not automatically linked, you can search for and select the desired fund:
  1. In the Blackbaud Online Express Plug-in, open the Donations link
  2. Place your cursor in the Fund column of the gift change
  3. Press F7 to load the fund picker and click Find Funds
  4. Search for the appropriate fund
  5. Click Open
  6. Click Ok