Hello, I have a under

Question

Hello,I have a under the fridge water filter for my ice maker. Two problems:1- I cannot remember how to release the pressure in the filter to be able to open the cylinder and put in a fresh filter.2- the current filter which is actually more than a year old still continues to put large sums of charcoal in my ice. It has done this from the day it was first put in and never has stopped.