Can I change to a U.S. tourist visa after my U.S. study visa is rejected?

Generally, it will not affect you. If you have a European visa, it will basically be more convenient to apply for the United States.

If you are traveling with a tour group, ask the tour group to sign it for you.

But if you are really worried, just change your Canadian visa. As long as the Canadian visa is issued, you don’t need to apply for a US visa, and you can still go to the United States.