Confusion with signal/source being low or high impedance
I don't agree with those statements by themselvas they intend to be generically true but they're not. If a sentence was added like:

Given two sources providing the same amount of output power, 
one having a low output impedance and the other having a high output impedance
Then:

High impedance source gives you more volts and less current 
Low impedance source gives you lower voltage but more current


Here's an example of both:







simulate this circuit &ndash; Schematic created using CircuitLab

Here the load and source impedance are the same, that's because I want to extract the maximum amount of power from the source. Both sources will deliver 2 Watts each.

Note how the power in my load resistor is 1 Watt in both cases. In the high(er) impedance case, the voltage is 10x higher but the current is 10x lower.