If you have no idea what the voltage is that you're about to measure,
then you should set the meter to the highest range before you connect
it to the two points in the circuit.
Analog meters indicate the measurement by moving a physical needle
across a physical card with physical numbers printed on it. If the unknown
voltage happens to be 100 times the full range to which the meter is set,
then the needle may find itself trying to move to a position that's 100 times
past the highest number on the meter's face. You'll hear a soft 'twang',
followed by a louder 'CLICK'. Then you'll wonder why the meter has no
needle on it, and then you'll walk over to the other side of the room and
pick up the needle off the floor, and then you'll probably put the needle
in your pocket. That will end your voltage measurements for that day,
and certainly for that meter.
Been there.
Done that.
