There are some options for customizing what your customers see when paying, but they are a bit tricky to find. I sure spent my sweet time in there looking.
First, log in. In the top bar, find "Profile". When you hover above it, a curtain will open with options, and you will feel like clicking one of them. Dont. Click on "Profile" itself.
Then you arrive at "Profile summary". Under "Selling preferences" you can edit various things and messages. If you click "Custom Payment Pages", I think you will find what you are looking for.