Two points:

1) Once when I offered My Dog Has Fleas, I received in return Your Dog Has Lice, which were the same notes but in the opposite order. I can sing 'em to you but not name 'em without having to think, which probably means something deep but in any case it suggests that the order is arbitrary, and neither mnemonic is "right."

2) The first (read "highest-pitched") four strings on the guitar, as it turns out, are the same as the uke strings except that the fourth string is an octave lower. BUT. That's only the "standard" guitar tuning. There are numerous other tunings (D tuning: drop the low E string ("sixth string") to a D; E tuning: raise the fourth and fifth strings a full tone and the third string a half-tone) I think. The five-string banjo has its own variations, too: C tuning ==> G tuning by dropping the lowest string a whole tone, for example.

Mnemonics are good for learning and we remember them fondly, but after a while they aren't needed any more. a bit like Puff the Magic Dragon...