There can sometimes be differences in the sum of transaction values versus the totals held in the nominal account records. In the first instance:
Establish if the problem is with Transactions, Records - or both - by comparing the TB reports with extracts of the Transaction Enquiry screen.
Check to see when, or if, the Trial Balance (TB) was last correct.
Then, our support team will need to investigate, run scripts or liaise with the hosting or development teams. Any Issues with contacting us, please see the following Get support in Access Financials., referencing this article and providing any findings from the above checks.