Help with a Brown & Sharpe Micromaster Digital Micrometer

[davidyat]

OK, the picture shows my Brown & Sharpe Micrometer with ONE yellow button. How do I change it from MM to INCH? The internet is useless. When I put in a new battery, the screen shows MM. When I press the yellow button, the screen says SET and when I turn the knob, the screen stays at 0.000 and won't change. HELP!
Grasshopper