Out Of Stock Variations

I have several products set up using variations with the purpose "Variations as one product" and I have the variation I want set as the default. If that default variation is marked out of stock then one of the other variations replaces it as the default variation. I can understand this concept and it's ok as long as the default variation is out of stock but when I add stock back into my original default variation it doesn't move back into the default spot. I have to mark the new default variation out of stock in order to move the original default variation back to default. Is there a setting anywhere to control this? I know I'm going to forget to do this occasionally and if the customer doesn't catch it on their end we'll be constantly questioning if they meant to order this variation (new default) or did they mean to order the variation they're used to getting (original default). I'm using version 4.12.2.SP1.