The VAT reports (VAT Return, VAT Analysis and VAT Detail - Listing) vary in how they total but are essentially built the same. They include certain transaction types and separates them by Input/Output and also VAT code.
However, journal postings are not included, so if a posting is made to the wrong VAT code, you can post a journal to move it between nominals but this will not be reflected in the reports, so if possible, reversing the erroneous posting and reposting it would be better.
If you need to check what transaction types make up the VAT for Sales or Purchase:
Enter the VAT Management screen.
Click the VAT DETAIL tab.
Filter into the different type (direction) and then the VAT code or Transaction Type.
Note: This gives you either a detailed or summary view, dependent on the radio button selected, per transaction type.