You can customize how you fund each Envelope and save the way that you fill them for next time! Here's how:
Enter a funding transaction using the the Fill Envelopes page as you normally would
Before you save, check the box next to "Remember this fill as..." and give it a name
The next time you enter a funding transaction, you'll be able to select which fill you'd like to apply.
If you need to make changes to a custom Quick Fill, just delete your old one by clicking the X in the Quick Fill drop down menu and save new changes the next time you fund your Envelopes.