The manual will include a matrix. For example: "For 154.600 MHz, set DIP Switch A: On, B: Off, C: On, D: Off..." Write these down on a sticky note.
Use a plastic spudger or a wooden toothpick (never a metal screwdriver). Follow the truth table in your updated manual exactly.
Open the manual to Page 2. Compare your radio’s internal circuit board color (Green vs. Tan) to the manual’s diagram. Tan boards often require soldering to change frequencies; Green boards use DIP switches.