QuickBooks Online journal entries are required to have a counter number, so the field can't be left entirely blank. However, you do have the option to control the sequence and use whatever counting scheme you'd like. See the instructions below to get started:
Setting up Custom Transaction Numbers
Begin by enabling the setting from the Gear icon (⚙) > Account and Settings > Sales tab > Sales Form Content section > set Custom Transaction Numbers to On > click Save and then Done.
Click the Plus (+) icon and select Journal Entry. Assign the first number of your new sequence in the Journal no. field.
Select Save and close. Beginning with your next Journal Entry, the counter will start on the immediately following number. For example, if you had entered ABC-1, the next entry will be numbered ABC-2 automatically.
This information is also available from our guide on custom transaction numbers for your convenience. I'm attaching a video below in which I set up a custom sequence for my journal entries:
Doing this will help you order your journal numbers however you'd like. Please keep in touch with me here should you have any additional questions or concerns. Thanks for coming to the Community, wishing you and your business continued success in all that you do.