Most people's (and grocers') freezers are set to the point that it is virtually imposssible to scoop ice cream immediately after taking out the carton. However, part of the appeal of ice cream is its texture from being frozen, so one must be careful when heating it. While it might work decently well on pints, using the highest setting of one's microwave is a good way to get a layer of cream soup on top of one's ice cream.

Given that the item you have is frozen, it makes sense that the best way to heat it up is to use your microwave's defrost setting. Even on microwaves with this mode, I usually just set the power level to 30%. This usually amounts to the same thing, but gives you the ability to make adjustments for further attempts should your first try not work out. I generally start at 40 seconds for a full half gallon, and scale down as appropriate as the ice cream level lowers over subsequent days. This gives a good compromise between being able to scoop it from the container and having it hard enough to enjoy eating. As always, YMMV.