VAT Journals will typically take the default bank account from the currency set up, and may need to be amended when posting journals for sub ledgers.
The default is also taken when a transaction is passed across to Access Financials via the Datahub from another application such as Access Pay and Bill. Since these transactions are batched by default it should be possible to amend the contra account before posting.
If the transaction has been posted then it will be necessary to enter a reversal manually