guitar fundamentals lv2, chords and scales

I'm kinda confused here when it comes to using the 1(root note),3rd (majord third) and 5 (fifth) to building chords from their respective major scales.

This formula makes perfect sense to me looking at the C Major chord but when I look at the A Major chord I'm kind of lost. If you look at the picture example in the lesson the A Major chord follows this pattern of the scale 1,5,1,3,5.

I was under the impression the formula is to be as followed 1,3,5,1,3 as it is clear in the C Major chord.

Maybe this is a simple solution and could answer my own question do you have to use the triad in that specific order or can you choose to put them in any random order and get a correct result?

never mind watched the lesson again, seems i was not paying close attention to what Chris was explaining. much clearer now