Problems with permissions

As soon as I try to activate the demo, WP forces me into a screen where I need to update the WP database. As soon as I do that, all I get when trying to login is “You do not have sufficient permissions to access this page.”

Then I have to delete the entire WP installation and start over.

Also, the slider doesn’t work at all, and of course I don’t have a code for it. It just shows “[layerslider id=”1″]” on the page where the slider should be.

I was watching this post and i tryed to fix that problem but i couldnt doit, can someone send some picks with the things that i need to rename please.