Yes...you charge your "3.7" IMR batteries on the 4.2 setting....How it works is Most Li-Ion batteries, regardless if they are ICR or IMR or IMR are labeled "3.6" or "3.7" volts because that is their mean voltage. That is that they are fully charged at 4.2 volts and then when you start to use them they drop down fairly quickly from their full charge voltage to 3.6-3.8 volts and sit at this voltage for awhile before they begin to drop again and should be charged ideally at 3 to 3.3 volts if not a little higher. 3.7 is the median or half-way point between 3 volts and 4.2 volts so that is what they are labeled as.
there is another type of Li-ion battery that has a special chemistry of Lithium, Iron and Phosphate. These batteries have a difference voltage range of about 3.6 volts down to 2.5 and their mean voltage or middle is 3 volts and that is what that three volt setting is for. If you would try and charge these batteries to 4.2 volts you would have a very bad reaction to the charging that might change the condition of your house from good to not good as these batteries aren't the most stable of chemistries and no Li-ion battery can be safely overcharged....overcharging is dangerous period.
Bottom line, if you don't know what a setting is for on your battery charger you probably shouldn't be using it. That goes for any setting. You can learn more basic information about the different types of Li-ion batteries here....
http://batteryuniversity.com/learn/article/types_of_lithium_ion
Does this make more sense now...if not I've got construction paper and crayons and paste and we can turn this into a class project because there is no such thing as too much battery safety information and even I reread this stuff every so often to make sure I have it down right.