Why can I not change my security settings to normal?

[AC Question]

Hello. I was trying to download an application today, but it said that it was unable to install do to some of my security settings... I look and I change my security level to normal, and I go back to try and download the application again. Same message pops up with the level going back up to high security. I really want this app, and I know it's safe. I would love to hear some replies

 

[SmItH197]

I am assuming these are apps that aren't from the play store, have you enabled installation from unknown sources? Settings->security->Check the Unknown sources box.