It depends on what system you use (Mac/Windows - what version, etc.) and what browser. I'm on a Mac, and in Netscape. To give more memory to Netscape, I would have to fid the application, click on it, then hit "Get Info" and go to memory, and type in a bigger number. To clear my image cache, I would have to go to my "preferences" selection under the Edit menu, then, in that dialog box, scroll down to advanced, and hit "clear disc cache now."

If none of this helps, post what your operating system is, and what browser you are using, and I'll try to help.