Transferring money between accounts is like taking money out of one pocket and putting it in to another. You don’t want it to show in your Money In or Money Out because you haven’t actually earned or spent anything, you’ve just moved it. So it’s best to take them out of the equation. Transactions categorised as “transfers” are hidden so they don't affect your balances.
If there are other transactions you want to hide for any reason, you can also just categorise them as transfers. Here’s how:
On the “Transactions” screen, hit the “Spending Group” drop down next to the transaction you'd like to hide, and choose the “transfer” option. You can also click on any transaction, which will open a transaction card, and you can mark it as a transfer from there as well.
Once you've hidden a transaction, it won't form part of your Spending Plan anymore.