Why are not the changes I upload to webserver visible in the web browser?

There is probably some chaching taking place on the web server, in your web browser, or somewhere in between.

Most web browsers have command that clears irs chache and requests the web server to clear its cache before reloading the page. Usually the command can be invoked using Ctrl+F5 keyboard shortcut.

If the above does not help or if you believe the server should pick up the change automatically, make sure the timestamp of uploaded file has proper value, so that the web server can recognise the file has changed.