Credit memos must be created in Manage, and applied in Quick Books Online. Payment records in Quick Books Online that contain credit memos must only be applied to one invoice; a credit memo can be distributed across multiple invoices by separating it into multiple payments - this is required by how Manage handles credit memos differently from Quick Books Online.
Better/more accurate payment sync.
We have encountered some situations in the current version that could have caused a partial-paid invoice to have a larger payment applied to it in Manage than in Quick Books Online. This is now resolved.
More information on how Gozynta Mobius handles Payments and Credit Memos.