How do you heat it up then? Or is it supposed to be drank cold?

I heat it up in the microwave all the time. Smooth as a pour-over and much less of a hassle to make.

That is the advise I got before, but I find this is super difficult to hit the right temperature. I either get boiling coffee, or luke warm.

When you get used to the microwave you have, you can hit the same spot every time. It's a formula depending on your cup, the wattage of he microwave and time.

I can hit the temperature I want every time on a Bosch microwave from 80s which has two power levels and a rotary, mechanical timer.

Also volume of liquid and temperature of liquid and cup.

And the age of the microwave.

https://www.psu.edu/news/agricultural-sciences/story/microwa...

I generally fill the cup to the same level, and fill it from the same source in the house in 99% of the time, so they are implicit constants in the equation, at least for me.

[delayed]

I drink my cold brew cold, although technically the "cold" in "cold brew" just implies that the extraction isn't from hot water.

I leave it on the counter to extract, and store it in the fridge.

This is what I do in the summer for cold coffee. Just throw a few tbsp of grounds and fill it up with water to the 32oz line and leave it overnight. Pour through a hario v60 with a chemex filter in the morning. You can also do it in batches and pour the filtered coffee into a larger jug and put that in the fridge and serve on demand from that. Filtered cold brew should stay good in the fridge for a while.

I've never liked cold brew, though of course that's just me. Blecch.