I know that the whole note has 4 beats, the half note has 2 beats, the quarter note has 1 beat, the eighth note has 1/2 of a beat, and the sixteenth note has 1/4 of a beat. That's how they explain everywhere. This holds true in a 4/4 time.

What happens in other time signatures? Isn't it misleading to say the whole note has 4 beats? Can a whole note have 3 beats/5 beats/2 beats? What will be the duration of a whole note/half note/quarter note be in other time signatures like 3/4?