Go to the “Quick Access” section and Click on the “Document Settings” icon present on it.
Select the box below “Default Invoice Prefix” and click on “Add New Prefix” from the pop up.
Enter your new invoice prefix and click on “Add”.
Congratulations, You have successfully added a new invoice prefix.
Note: You can always edit the Invoice prefix later.
Close "select prefix" and Click on “Update Document Settings” from the first form present at the bottom of the screen.
Congratulations! You have successfully added a new Invoice prefix, and a pop up appears at the bottom of the screen informing the same.