dreamweaver css strange behaviour

Hello everybody,

I'm working with Dreamweaver since some time and never paid attention to CSS until these days.
No big problem creating them BUT they acting strange.

I have no more than 4 styles; TITLE, TITLEDOWN, TEXT and FOOTER

The fact is that I use TEXT most of the time BUT Dreamweaver always tries to create new styles, no matter if I force it to use the existing ones.

Example: I copy/past without formatting some text. I select it, choose style (TEXT) and it's okay.

I keep writing just after the copied text and it appears as Style1 and so on.

If I add bold or italic to TEXT, it changes to Style2-3-4-5 or the number that continues.
I premuse that adding bold-italic-underline it's a new style and it's okay, but.....why is not doing the rest good?

Another thing is that TEXT have 11pt font size.
Today, TEXT appeared as 4px as font size. Why? It's well and clear that it got to be 11pt.

No idea guys,
Is it possible to make DW not create new StyleX....or any extra options for CSS an DW??

Thanks!