How to stop defaults?

In 5.1.1 if I had multiple apps installed that supported the same action I was presented with a choice and 2 buttons: "use once" and "use as default". This allowed me to pick different apps for different use-cases.
After upgrading to 6.0.1 whenever I'm presented with such a choice, as soon as I pick an app I get a message that it's now a default app.
How can I stop that behavior and allow me to keep selecting different apps on case-by-case basis?

S7 defaults to MTP not charging

I have a very weird issue, my S7 actually defauts to MTP even after I select charging in developer settings.

If the USB is unplugged and I try to change it away from MTP it just stays at MTP even though I select any of the other options.

and if I change it when my phone is plugged in it changes fine, but if I unplug and plug it in again it reverts to MTP.