I have tried changing the portfolio slug in the theme options, and each time I do, the links to each portfolio item give me a 404 error. When I change it back to the default, they work perfectly. Please help, this is a must change for my client!
Please reset permalinks.
If necessary, set them to default, find and rename the .htaccess file and then reset permalinks to ‘%postname%’. This will rewrite the url rules and eliminate the problem.