Some things have on my iPhone are in Spanish, and some are in English?

A couple weeks ago I changed my phone language to Spanish because I'm going to Costa Rica and the Dominican Republic soon so I wanted to practice my Spanish. But I changed it back a few days ago, but a lot of things are still in Spanish? Why? How do I fix it? I have iOS 11.2.6 and the iPhone 7plus if that matters any

Try rebooting it.