This may be caused by one of the following:

• Manual check updates Last Check number is selected in AP Settings, Payment Settings.
• The manual check is actually being recorded as a Quick Check and Quick check updates Last Check number is select in AP Settings, Payment Settings.

• Unmark Manual check updates Last Check number in AP File, Company Settings, AP Settings, Payment Settings to prevent any future manual checks from updating the last check number on the CM bank account.
• In Tasks, Record Manual/Print Quick Checks, verify that that the Payment type selected is Manual Check when recording manual checks.

If you need to correct the Last AP Check Number on the bank account, refer to DocLink: How do I change the starting check number for Accounts Payable or Payroll checks?