Using a piece of tape with a small fold in the top, number all your resistances from one to four. You will write the number on the tab of the tape so that from the top of the resistance, you can always see what number it is. Below we have three pictures of the same circuit. Draw on each one of them where you need to insert the current sensor to measure the current going through resistance one, four, and two or three (resistance two and three have the same current)