How to apply? According to most reviews, easy & very helpful app. My issue, 1st no permissions needed, then how to apply the app, based on camera, size of phone...what? It does measure more than 2"? I am not stupid 😞, I know how to use tape measure etc..Just don't know where it is sometimes. Sorry for the ignorance, information can make a world of difference. 🤷‍♀️