Not all browsers will show the newer picture, instead they will use a picture from a cache stored on your own computer
Here are the solutions:
Click, 'Refresh' or 'Reload'. You may need to hold 'Shift' at the same time.
Or:
Netscape 3.0 and Internet Explorer 3.0, the refresh feature works with the default settings
Netscape Communicator 4.01 to 4.05. There seems to be no solution for these browsers, they will not update automatically
Netscape Communicator 4.5 and newer Ensure that 'Every time' is checked under "Document in cache is compared to document on network:" on the Edit/Preferences/Advanced/Cache menu.
Internet Explorer 3.0x (and newer) Ensure that 'Every visit to the page' is checked under "Check for newer versions of stored pages" on the Tools/Internet Options/General/Temporary Internet Files/Settings menu