Welcome to the thread, wiemergal.
I'm here to lend a hand about your budget concern.
The Customer option filter in the Budget vs Actuals report in QuickBooks Online (QBO) will show up depends on how you create the budget.
If you didn't select Customer in the Subdivide by drop-down menu when creating a budget, then, that is the reason why it isn't showing on the filters when you try to customize the Budget vs Actuals report.
For more information about the Budget feature in QBO, see this article: Create and import budgets into QuickBooks Online.
For additional reference, you may find below links helpful:
Get back to me on this thread and leave a comment if you have further questions. I'd be glad to answer it for you. Have a nice day.
