Lots of people start over to reorganize, or because they stopped using YNAB for a while and just want a fresh start.
Step 1: Go to the File Menu and select Make a Fresh Start.
A pop up will appear:
Click “Make a Fresh Start”.
Step 2: Right click on the account in the sidebar to update the balance.
Click on Adjust Account Balance in the pop up that appears.
A second pop-up will appear:
Enter the new balance and your starting balance will be updated accordingly. Now you are all set and can move over to the Budget and put those dollars to work!
Go to File > Open to reopen it. The name of your old budget will have the name you gave it, followed by the words "Before Fresh Start on" and a structure similar to this:
MyBudget Before Fresh Start on 2012-12-05~NCC1701D.ynab4
Your old budget may be located in a different folder. YNAB saves your budget in one of 2 locations dependent upon whether you're using Cloud Sync or Local. You can see and edit where those folders are located by going to File > YNAB Preferences in the YNAB 4 menu.