Hi SusanCruseBurke
You are not able to amend the statement template however to assist us with your requirements, and hopefully get them implemented, we would be grateful if you can leave feedback from within the product.
In regards to the invoice you can add your bank details in the footer section of the invoice, select the cog/gear icon in the top right hand corner of the screen > custom form styles > content > select the bottom greyed out area on the right hand side of the page > enter bank account details in the 'Add payment details and footer' > Done.