Manually adding a transaction in the bank register. Why does the deposit keep defaulting to a check once amount is entered?

Let's get this sorted out, morris. 

You might have input the transaction amount in the Payment column. Once the amount is entered in this column, it will be automatically categorized as a check since checks is typically used to record payments. To record your deposits in the Bank Register, you need to enter the amount in the Deposit area so that the program recognizes it as a deposit. I will provide an image for visual reference.  

Moreover, I'll add these articles to learn more about handling your deposits in QuickBooks Online (QBO): 

• Find, review, and edit transactions in account registers in QuickBooks Online
• Transfer funds between accounts

Comment below if you have more questions about managing your deposits in QBO. Keep safe and have a good one!