Quigon has full health and 1 shield. I roll 2 dice both 2 shields. I want to hit him with all four shields. He states that Quigon is similar to dooku and that I can only hit for 1 shield on each die and I have to stack up the remaining shields to 3 shields. I thought as long as you have 1 shield you can use any shields you gain as damage?

Once per time receiving shields. So even though you can gain 4 shields, quigon is worded so that you can only do his special ability once per gain. So even though that dice has 2 value, only one of those two can be given as damage, but if you claim two dice, you would be able to do 2 damage.

Qui-Gon's ability is "before" and limited to one. So he has to have an existing shield to convert and then only once so:

1. Convert the existing shield to damage removing it, then add 2 shields.

2. Convert one of those to damage and then add 2 shields for 3 total.