Of course i will explain to the best of my knowledge @j85063.

You can change your daily quest by clicking the New Quest option as seen in the image below. Please note, you can only do that once and if you have already won any daily quest battle, changing it will cancel your quest and you have to start all over again i.e. completing new 5 daily quest.

I think you mean Potions and not Options. There are different potions at the shop section which are meant to help you get better reward. The Quest potion (the max.) adds 5 cards to what you claim, for instance, if I have the max quest potion when I complete my daily quest, at gold I league i am supposed to get 8 cards but because I have bought the Quest potion i'll get 13 cards, that's 5 extra. We have other quest potion that will give you 3 and 1 extra card(s). But this will be changing after the update on 30th November.

We have other potions that will improve your chances of getting a Gold or Legendary card.

We also have the mystery potion that gives you a gift daily.

I do hope the explanation helps.