The tab button moves 8 spaces, but I would like it to move 4 spaces.
To make a Netbeans tab for 4 spaces: Click Tools → Options → Formatting. To set the tab size, there must be a "Tab Size" text box (see figure below).
For PHP users, in case the "Tab Size" field is disabled, change "Language" to "All Languages" as shown above (Willmore's answer). Then the Tab size for PHP will be what you set there for "All Languages".
