Hi April_van_Buuren,
I think you can not change the letters in more details, youv’e got only the normal settings. I think it is not good to use it as an template print out because to make it look like a letter you have to add text/content/the reason for the letter and this is different in every letter. You only could write the letter for each customer in quickfile and print it when ready. If you need write some letters offline you could may re-build it in word or so?
You could may use the invoice templates (it depends for what you want to use it) because you can actually change quite a lot in Quickfile invoice templates to make it your ‘own’. If you want to change more detail you can use the css editor. Just go to any invoice you created so far and click the green button top left ‘Invoice Style Gallery’. All the examples pop up. On top of your current one you can see a yellow bar ‘Change Style’. If you click it the css editor open.
For more info how to change things around you can read:
I hope this helps