All invoice items posted to an invoice in the past can be found in the Invoice items overview, in the Financial module.
Use the filters to display the invoice items you want to see. In this result, you can select all invoice items at once or individually by ticking them. Then click the ‘Edit’ button in the box below the filters.
A pop-up will appear where you can change the ledger account, the VAT rate, and the ‘counts as rent’ status of the invoice item(s). When you are done, click ‘Continue’ to save the changes.

Ledger account

Choose the ledger account to which the invoice items should be posted. You can also leave this set to ‘unchanged’.

VAT rate

Select the correct VAT rate. You won't find an ‘unchanged’ option here, you have to make a selection. ‘No VAT’ is one of the available choices.

Counts as rent

Select whether or not the invoice item counts as rent, or maybe you want to leave this unchanged.