The invoice is locked

Or maybe you are finding that you cannot make edits to your customer records? 
Once an invoice is synced to Quickbooks, it can't be altered in Kickserv. So, you will have to make your needed changes in Quickbooks and run the sync to get the info updated in Kickserv. 

The same is needed for edits to customers. When you make a change to a customer record in QB, it will update in Kickserv on the next sync.