You're confusing a couple things.
If you go to
www.lyngsat.com, you will see that each of the satellites have transponders and associated frequencies.
Think of them as channels on an FM radio.
You must set your receiver to an 'active' frequency to get some signal, just as you could set your car FM radio to 92.5 and if there is no radio station in your area on that frequency, you wont hear anything.
Now, the 10750 is the frequency that your LNB needs to operate. That will not change. Your box has settings for LNB type (circular or linear) and the frequencie(s) it needs (some linear are dual frequency). The circular LNB's for Dish and Directv use a different setting than the linear LNBs.
Hope that makes things clear as mud..