I only have high and low settings on my crock pot?

I just bought a crock pot and i am trying it out for the first time today. The receipe calls for me to set my pot on medium heat for 6 hours. My crock pot only has the following settings : 4hours high; 6 hours high; 8 hours low; 10 hours low. I have read many recipes that call for the medium setting. What do I do? I can still return it. Do i leave it on the high for less time or the low for more time than noted? Thank you for the help!