Hello there, @econnolly.
Adjusting the address alignment on preprinted checks for bill pay is currently unavailable in QuickBooks Online (QBO). I can see how this feature would be beneficial to you and other businesses.
While we continue to make your experience with us even better, in the meantime, I encourage you to star our blog to keep up with any product updates or improvements on the online version: QuickBooks Online Blog.
To learn more about printing forms in QuickBooks, adding you some articles which you may find helpful:
You're always welcome to come by the Community if you have additional concerns. It's my pleasure to help. Have a fantastic day!