Where to change date dd-mm-yyyy to yyyy-mm-dd

[Myggan]

I have try different way in the language fil to change to format yyyy-mm-dd and some pages works ok but in advance search dont work, and some problem in registration.

There must be somewhere else to change this function , i also want to have in registration the swedish person number like yymmdd-cccc

c is controlnumber

I am a newbie on this, so i be WERY happy if anyone can help a bit..

Thanks