If you've run into odd behavior with Safari, one convenient way to empty caches and otherwise clear temporary data is to use the "Reset Safari" option in the "Safari" application menu. Despite the convenience of this feature, some people may wonder what will happen for each option, and what might happen to personal data.
Apple has a brief description for each what each option does if you click the purple question mark in the Reset Safari window; however, people have asked whether they should be concerned about any options, especially if they would like to preserve saved settings and registration information for various Web sites.
The only options that contain personal information in Safari are Cookies, AutoFill form text, and Saved Names and Passwords (which is just a subset of the AutoFill information), and of these, the only items that make a difference in terms of preferences and settings for websites are cookies. All other options just remove temporary items that increase Safari's browsing speed and the convenience of autofill features (though the inaccuracy of this can sometimes be a frustration in itself).
If you are experiencing odd problems with a single website, instead of removing all cookies using the "Reset Safari" feature, do this by hand and use the "Reset Safari" option for all other temporary items. To clear cookies for a site by hand, go to Safari's preferences and click "Show Cookies" in the "Security" section. Then search for the domain of the site you are having problems with, highlight just those cookies, and click the "Remove" button.
After this is done, go back to the problematic website and see if the problem persists. You may need to change user-specific settings again, but you will not have to do this for all of your Web sites.