Default Internet default atorage download folder keeps changing

Hi guys bit of a weird one - in my stock internet browser i have gone into settings > advanced > default storage and changed it to memory card a few weeks ago so that everything i download goes on to my 32gb genuine samsung class 10 card. Everything performs great for a few days/weeks but every so often i notice that the setting reverts back to "device" and i have to go back into the settings and change it again. Its nothing major but a little annoying nonetheless as i often download large zip files that i need to go onto my sd card.

Anyone had any experience with this and have a way to stop it happening? Im keeping an eye out on any third party apps or anything i may do or run that might cause this.