I’m guessing that you are meaning the recording Pings Per Second menu setting here: go to the Snapshot and Recording View. Open the X-press menu and the Pings Per Second menu should be at the bottom of the list. Highlight the menu and use the Right Arrow button until the menu setting shows as “Auto”.
To turn off the lower frequency (assuming the 2D sonar here): go to the Sonar menu tab and set the Beam Select to the “200kHz” setting.