USB Connection type setting not sticking

[scrondar]

So, I'm still on Marshmallow and found a site that showed how to setup the USB connection type to whatever you like, in the Developer options. Problem is, the setting I chose (MTP) does not stick, and I still have to pull down the notification to get to the settings that move the phone off USB charging and on to MTP when connected to my PC. Anybody have an idea how to make this setting permanent for PC connectivity?