How do i set up customer job option on write checks page?

Hi, longlet.

I can help enable the option to set up Customer:Job when you write checks in QuickBooks Online (QBO). 

QBO has a Project feature that functions in the same way with QuickBooks Desktop's Job Costing feature to track expenses for a job. Here's how you can add the Customer/Project column when you write checks in QBO:

1. In your QBO account, go to the Gear icon.
2. Select Accounts and settings.
3. Select Advanced.
4. In the Projects section, toggle on the option.
5. Choose Save, then Done.
6. Create a check and see if the Customer/Project column is added.

 Let me add this reference about managing projects in QBO: Create and manage projects in QuickBooks Online. 

Like job costing reports in QBDT, you can run Project Profitability and other project-related reports in QBO. Let me add this article as a guide in running these reports: Run reports in QuickBooks Online. 

We'll be here in the Community if you need further assistance customizing checks or expense transactions in QBO. We're committed to offering ongoing support. Have a good one!