Money transfers between your accounts should not be counted as spending or income. They are marked as internal transfers. If you notice transactions that were really transfers, simply change the category to "Internal Transfer" and it will be hidden from your spending/income reports and numbers.
Credit card payments can be tricky. If you have connected a credit card, the spending on that card is already being displayed on the Reports tab. Therefore, we don't want to count the actual payment of the card as an expense as well because it would be double counting.
As such, payments to credit cards that are connected to Truebill should be categorized as "Internal Transfers", while payments to cards not connected to Truebill should be categorized as a spending category of your choice, or bills.