The L.O. is fixed. What it is is determined by the LNBF. Common L.O. freqs: Standard Ku= 10750, Universal Ku=22khz off-9750, 22khz ON-10600. C band=5150 (their are others)
For Ku, subtract the LNBF's L.O. from the TP freq. Result is what the receiver actually tunes.
For C, Subtract the TP freq from the L.O, Result is also the freq the receiver is tuned to.
Your entry of the L.O. into the receiver is only for the receiver to calculate and display the TP freq.
If you enter L.O. 10600, but the actual L.O. is 10750, the receiver will still 'blind scan' transponders on the satellite, but all TP freqs it displays will be 150Mhz different from actual.
When you enter the L.O. and TP freq, the receiver can then calculate what frequency to tune to.
12200 - 10750 = 1450
11700 - 10750 = 950
The frequencies- 950 to 2450 are often referred to as "L" band.