WordPress want me to install it again

I set up my webpage localy at my computer, using wamp. Thing is, I didn′t do a proper wp-config set up. Now when I am ready to upload my page to the web I changed the wp-config and now wordpress dont understand that it is installed. When I changed all my settings back to what I had before it is the same problem, wordpress just asks me to install it againg.

So two questions,

1. Why dosn′t wordpress work with my old settings?

2. How can I change my wp-config to the proper settings and still make it work?

If I can just acces my page with my old settings maybe I just can export the page, then change wp-config settings and then import it againg?

I will be enourmusly thankfull if anyone can help me since I am starting to panick a little bit.