Change text on checkout page to reflect correct amount

Hi,

I am looking for a solution on how to change the text that appears on the checkout page, before making a payment. When a coupon is applied, the text is updated to say, "you will pay $x.xx each month" this is not true. Each coupon is only for 1 month and the text should be corrected to "$x.xx for the first month and $x.xx for each month after."

See screenshot for reference. Thanks