If you are making changes to your WordPress site but not seeing them online, there are several things which could be causing it and which ought to be looked into.
First, and foremost, simply try clearing your browser’s cache. See: Clear Cache For Your Specific Browser
If you don’t want to clear your cache just yet, you can try a force-refresh first.
To do a force-refresh in FireFox simply hold down the Ctrl and Shift keys, then press the R key. In Internet Explorer, hod down the Shift key while clicking the Refresh button. If you are using another browser, try these same two combinations as they often work in other browsers as well.
You can also try testing your site from a proxy site such as ninjaproxy.com, and load your page from there. Proxy sites show you what an un-cached version of your site looks like to other people.
If the problem persists, check to see if you have any caching plugins of your own such as wp-super-cache etc. If you do, any of these plugins could be causing the problem. If you don’t have a caching problem, it still could be a plugin problem. For fixing plugin problems see: http://wordpress.shadowlantern.com/2010/10/fixing-wordpress-plugin-problems/
Most caching plugins have the built-in ability to delete their caches. Try the built-in tools first. If it doesn’t work, rename the caching plugin from within the plugins directory and also rename any/all cache-related files in the wp-content directory.
If you still have problems, make sure you are on the latest version of WordPress. Also make sure the time stamp on your post and the expected time stamp in Settings > General are matching. Take daylight savings time into consideration if you have daylight savings in your area.