Hi,- " if we define the electron as negative and read 10 amperes, then if we change our minds and define it as positive we will still read 10 amperes. "
Is this because the ammeter will measure current (electric current) as how many electrons are flowing right through the clamp at that moment regardless of the charge it carries at that moment.
Well if you want to get technical, current is almost always measured indirectly. Usually by a force due to an electromagnetic effect. Even more indirectly of course is the voltage drop in a resistor, or the Hall Effect.
The meter would measure the same current if 100 holes passed in once second or 100 electrons passed in 1 second, but the holes would be going in the opposite direction as the electrons. Obviously if we change the polarity then everything reverses. Ammeters do have a polarity.
