How to change the low gain option to high gain option in Mark Levinson No 25S

Hi!
  In page 10, there is  explanation about the gain change for gain option in each setting (low option (MM) (38 and 44dB) to high option (MC) (58 and 64 dB))   but no explanation for changing low-gain option (MM)  to high-gain option (MC). So if anyone know the how to change this option, kindly let me know. Thanks.

From the manual:

The Nº25 is available with "EITHER" a high-gain or low-gain phono option. Each option offers two internally adjustable gain settings via two twopole miniature rocker switches, one for each channel. The high-gain and low-gain phono options have been factory-adjusted at the lowest gain settings (58dB and 38dB, respectively).

You can’t change from low to high. It is an either low OR high, but not both.  It would depend on which version was initially ordered.

Thank you for clear answer.