Emma, Jubilee, Psylocke, and all the others

This is another issue I can’t get my head around – if the original movies (the first Wolverine included) present some mutants as adults (or in their late teens), why do the follow-ups dismiss these details?
Such is the case of Emma Frost, one of the most powerful telepaths in the comics. The problem is that she appeared in the first Wolverine flick as being in her late teens, only to appear in First Class (which is set quite some time earlier) as an adult.
The same goes for Quicksilver (who only cameoed in the first Wolverine flick), as well as some of the other mutants.
And then there’s Psylocke, who also appeared in Last Stand before Apocalypse. And the same issue applies, with another one added to the mix – the change of superpowers. In the comics (as well as in X-Men: Apocalypse), she is a powerful telepath with extraordinary telekinetic abilities, but in Last Stand she is a teleporter. Bend your mind around that.
It can be explained, of course, since many times in the comics the characters get upgrades. But still – these aren’t the comics, and a bit of continuity wouldn’t hurt.
