Adaptive ad and ap damage with the new runes

Hello, as a support main I'm having some problems due to the new runes with adaptive ad/ap damage.

It seems that champions have a "preset" set to full ad damage or full ap damage bonus when you start a game, that you can move to ap if you chose an ap starter (doran ring) or ad if you buy an ad one (doran sword).

By buying the relic shield on Leona for exemple, I am locked with bonus ap, and since I won't buy any offensive item, the rest of the game will follow with an ap bonus. Before the preseason I was using ad runes and I would like to continue but with this change I am unable to. Is it possible to be able to chose what "adaptive" damage you want with the runes you get to take or are we goona have to deal with some champions being unable to change their bonus ?

I noticed too that if you buy any as/crit build without ad you'll still be locked with the ap bonus if it was the default one you got as you started the game.

I'm sorry if my english is weird, thanks for reading.