Get more coffee, less ice/milk
This one should be a little obvious, but we're going to lay it out here just in case you missed it (no shame). When you get an iced coffee, your 'Bucks barista will usually load that sucker up with handfuls of ice, and if they put the milk in themselves, they pour liberally. In the long run, it saves the chain money. We get it. So, simply ask them to go light on either one, or both, and they'll comply. Say please, though. It's just common courtesy.