How to link sales reps to customer accounts.

Welcome to the Community, Morne. Let me give the steps in linking sales reps to your customer's accounts. 

In QuickBooks Online (QBO), we cannot directly assign a sales rep to a customer profile. We can create a new field that indicates sales reps or classes in the Custom fields. Just ensure that you enable the custom field and set it to appear on the form. Let me guide you through the steps.

Here's how: 

1. Go to Settings ⚙ and select Custom fields.
2. Tap the Add field.
3. Note: If this is your first time creating a custom field, select Add custom field.
4. Enter Sales Rep in the Name field.
5. Select the All Sales forms or Purchase Order checkbox.
6. (Optional) To show the custom field on printed and delivered forms, turn on Print on the form. Otherwise, it will only appear in QuickBooks Online.
7. Click Save.

After that, we can customize the Sales by Customer Detail Report by adding the Sales Rep column to show the data regarding the sales rep that you want to be part of the report.

Here's how:

1. Go to the Reports menu and click Sales by Customer Detail.
2. Tap the Switch to classic view button, then change the date range from the Report period and pick the correct Accounting method.
3. Tick on the Customise button, then select the Change columns link.
4. Place a checkmark next to Sales Rep.
5. Choose Run report. 

Also, another option is to track your sales reps in QBO using the class tracking feature so you can run sales reports by class. However, this feature is only available in the QBO Plus version.

Additionally, I've added this article for your reference in personalizing sales forms in QuickBooks Online: Customise invoices, quotes, and sales receipts in QuickBooks Online.

I'll be on the lookout if you need additional assistance assigning a sales rep to a customer in QBO. Have a nice day ahead!