After entering hundreds of receipts, is it possible to exchange a bank account for another in one step, through a query, for example
Your question is not clear. Are you trying to batch-update payment transactions? You can easily do that with batch operations
Read this guide: Use Batch Create and Batch Update functions
It is all explained in the guides provided by @Abeiku. If you are unsure what and how then just create a test business and experiment. Always good to make a backup of your business before doing any batch actions as well.
@mgaber, there is another aspect to your request that has not been addressed. Why do you want to exchange one bank account for another?
It would not be appropriate to change bank transactions to a different account than the one where they occurred after the fact. That would be fraud.
However, if you mistakenly defined a bank account incorrectly, you can correct all related transactions in that account simply by editing the bank account definition itself. For example, suppose you named a bank account as “Merchant Bank of Arabia,” but later realize the correct name of the bank is “Arabian Merchant Bank.” Editing the name of the bank in the Bank and Cash Accounts tab will change the name on all receipts and payments entered.
Of course, if there was just a clerical error, where the wrong bank account was selected when transactions were entered, Batch Update is the way to go.