One of the advanced features of the new BitBoxApp is Coin Control. It adds a privacy enhancing capability by allowing you to choose which unspent transaction outputs(UTXO) you want to use for your transaction.
To enable coin control go into the BitBoxApp settings and under “Expert Settings” tick “Enable coin control”.
Select the UTXO(s) you want to use as inputs for your transaction.
Now just fill out the transaction details as usual. Keep in mind that only the UTXO(s) that you have selected will be used as inputs which means that clicking “Send all” sends the sum of the selected UTXO(s) (minus fees), not your whole account balance.