Sometimes your letter may have the wrong merge fields, some times this can just be a matter of setting up the wrong one but it also could happen in the move from Live to Liquid due to field names changing.
- Go to System - Document Templates
- Find the letter you require, click on the drop down arrow and click Edit Document.
- Find the merge field you want to change or replace, put your cursor into the middle of the word
- Right click and click on delete field
- Now leaving the cursor where you want it
- Go to the top of the page, you will see palace merge fields
- Either scroll through the list or click into the list and start typing the name of the merge field that you want.
- Click on it and it now sits in your letter
- When you have finished, save and close