How do I change language to English?

Are you referring to the overall site language? If yes, you can change that in the Account - Settings page:

https://www.jotform.com/myaccount/settings

If you are referring to the form translation, you can do that in the settings page of the form builder. The below guide will help you about it:

https://www.jotform.com/help/298-How-to-Make-Your-Forms-Multilingual