Missing edit button for App Customization on iPhone 12

How do I edit my apps on IPhone 12? Like if I want YouTube to be a different color like a darker shade of red or something. People have found the edit button by holding the screen until the apps wiggle and clicking the plus sign and it shows their edit button. But when I try to do it on mine it does not show the edit button instead it takes me to search widgets. Does anyone have this same problem and know how to fix it?

[Re-Titled by Moderator]