When you create a Java applet in NetBeans, the NetBeans IDE automatically creates an associated HTML file which controls the startup size of the applet. If you want to override this, you cannot simply edit the generated HTML file, as it gets overwritten each time the applet is run. Do this instead:

1. Copy the generated HTML file from the “build” folder to the “src” folder, then
2. Edit the HTML file in the “src” folder as needed. This HTML file will function as an “override” file, and will not be overwritten by the IDE.