Without knowing more about the unit you're using, all I can do is guess. But when you said 'DC Volts 10A' that doesn't sound right. Often a multimemter will have a specific place to hook the red probe up to for measuring only high (relatively) current, that will be marked "10A" (or whatever the higher range the meter can use is). You don't want to be plugged into that when measuring voltage.
Here's a typical basic DVM:
Notice the unused probe connection labeled 10A DC? that one gets used for measuring current (amperage) only, nothing else. In this picture, the probes are attached the way you'd want to when measuring voltage. Then you would select DC Voltage (V... NOT V~ in this image) and pick the smallest range that will include the voltages you expect to see (20 in this case).
Helps?
Here's a typical basic DVM:
Notice the unused probe connection labeled 10A DC? that one gets used for measuring current (amperage) only, nothing else. In this picture, the probes are attached the way you'd want to when measuring voltage. Then you would select DC Voltage (V... NOT V~ in this image) and pick the smallest range that will include the voltages you expect to see (20 in this case).
Helps?