When taking a shower, I have to turn the hot water on all the way and the cold water on only a little bit and then it always seems that the hot water never lasts long. Could this be a problem with the way that my knobs are attached or is this a water heater problem?

Lets first take a look at your water heater. How hot do you have it set and can you give us a temperature reading of the water at the spout? You could have a bad mixing valve situation but lets first insure your heater is set properly. Also, how long ago was the heater installed?