It sounds like the clicking noise might be sounding at the beginning of notes as well as at the end. Clicking is almost always caused (in my experience) by the sample start and end times cutting into the sound being played. Changing the release like you did should be the right way to stop the end of the sample from clicking, so hopefully you're good there.
For the beginning click, open the sample and hover your mouse over the left edge of the blue area where the sample is shown. You should be able to click and drag your mouse left and right from there to change the sample start position. If you can't fix the clicking by changing the start time like that, then you might want to try and re-record the sound you're sampling, but start recording well before you play the sound to sample, that way you can move the start position to where the sample actually starts.
Hope that helps.