I have received the attendee's offline payment, how can I mark the payment as completed and move the attendee in the approved list?

When the attendee selects the offline payment method to submit the registration, the attendee status will be "Pending (Approved).

Once the attendee's offline payment status has updated as completed, the attendee will automatically go to the approved list from the pending list.

Update the payment status in attendee's order details 

Step 1: Go to RegOrder Page and click into the attendee's order page.

Step 2: Click the "Mark as completed" button.

Step 3: Click the "Confirm" button to process the payment status update.

Step 4: The payment status will successfully mark as "Completed" and Payment Receipt will also send to the attendee automatically.