LyX ⇒ Equation Alignment

[PLuz]

Hello, i'm a new user so sorry for anything that I do or say that I shouldn't do...anyway:

I've been wrinting a document for quite some time using lyx. The document has various equations and everything's been fine: numbering, alignment,etc. Now all of a sudden any new set of equations I creat are right aligned. I've tried every environment, ams aligned, ams alignedat, equation aligned, equation alignedat,...

the old ones are fine, just the new set of equations are right aligned. I can change the alingment in the lyx document (and they look fine) but in the pdf preview they remain the same (right aligned)...please help.

Thank you