Can’t get into mail app

I had to change my yahoo password. Changes it in my computer and iPad. When I go to change it in my phone the section under settings, accounts, mail is grayed out. As is my iCloud bar. It won’t let me change my password. When opening my mail it tells me to go to settings, select the mail account and enter password. However the section for that isn’t bold. I have shut the phone down and updates the current settings. Everything works but my mail and iCloud.