Guys, I really need your help! I am using XIAOMI 4 and this phone does not have a built-in lock. I need to lock my photos and videos because I sometimes need to show pictures to my colleague and they just had the chance to saw all of my photos.I don't have anything weird in my gallery but it's just felt strange that someone just go through all your photos. I heard there are some good apps designed for lock apps, but I have never used any of them before. Especially some of them just lock all your gallery instead of lock individual photo. There is one app called AppLock and it seems to have tons of good comments, I heard they can buy good comments on google play, so I need someone who really used it before to tell me if this app good or not! Thanks ahead!