Why is Lollipop kicking me out of Settings and showing a PIN screen?

[CopperBrass]

Hello.
My phone is a Samsung Galaxy S4, using 5.0.1. Smart Lock is NOT enabled and NEVER has been. I have been unlocking my screen with a draw pattern and not a PIN. Phone has been working problem free in every regard for about 2 years, and has been running Lollipop for a long time (months, maybe a year, IDK). I can still use my phone in every regard except for the Settings menu. Whenever I go into Settings I get kicked out and see a screen asking for a PIN. The screen has the little white gear with a blue circle in it (icon for Settings) and a number pad. That's it. Punching in the 4 digit pin I used a long time ago before I switched to the draw pattern to unlock my screen doesn't do anything. I can still use the "Go Back" arrow at the bottom right corner of the phone to leave this screen, so I can still use the phone and all apps. But to get back into Settings again I have to restart the phone, go into Settings, and finish whatever I am doing there within a few seconds before it kicks me out again and pops that screen. It's frustrating as heck to troubleshoot because I keep getting kicked out!

 

[nahoku]

Yes, that does sound frustrating! Almost sounds like something malware might do.

Have you tried starting your phone in Safe mode to see if some app is causing the issue? Safe mode will disable user-installed apps. If it works, then you'll need to determine which app might be causing the problem by uninstalling them one by one. A real PITA for sure.

Note... link is a generic Google search result because you didn't state your carrier. Just look for your carrier and follow the directions to Safe mode.

 

[CopperBrass]

Thank you for your reply.
Got some help and it turns out it is the Applock app I have on my phone, an app I haven't used in some time, but I still remember the password for it. Entering the password unlocked Settings. Don't know how Applock decided to lock down Settings, but I just need to go into Applock and configure it properly now.
Thank you.

 

[nahoku]

I haven't used in some time, but I still remember the password for it

Lucky you remembered it! Glad you got it worked out.