Why do random apps keep installing themselves on my device

[AC Question]

First noticed the problem a week ago when my husband opened the device it asked him if he wanted to open app using Hola or Launcher. We didn't touch Hola and just used regular launcher. Spent a week trying to uninstall it but it keeps coming back. Wen to delete it via Google Play - it showed up there but upon selecting uninstall the device told me it was not installed by GooglePlay do you want to uninstall anyway. I chose yes and it has since been coming back. Other random apps have been installing themselves since then. After a week of trying to get rid of Hola I decided to do a factory reset - chose not to have any data backed up before doing this. Apps still randomly install. Did another factory reset, changed google account and password via PC not logged into any google account, no apps installed on device and still problem persists. Ads for apps keep popping up on notification bar, some of which install themselves on device. I long press on the app in the notification bar which takes me to the app it is associated with and it comes up with App Market with an Android robot next to it. I don't know if this thing came with the original device but it does not appear on any other Android devices in the house. There isn't an option to remove this. I have pressed Force Stop on it, unchecked notifications from it and disabled it. Not sure if it is going to work or if there is something more sinister going on with the device. Can anyone suggest a more permanent solution?