Managing a server
Game settings
Change the common Minecraft settings in a form.
This tab edits server.properties for you. It shows the settings most people change: the message in the server list, player limit, game mode, difficulty, whitelist, view distance, port and more.
Change what you want. Before you save, a box lists exactly which lines will change. Press Save game settings, then restart the server.
Only settings your version of Minecraft has are shown. Everything else in the file is left exactly as it is; edit those on the Files tab.
If the tab says to start the server once, do that. Minecraft creates its settings file on the first run.
Leave Check players own Minecraft on unless you know why you need it off. Turning it off lets anyone join under any name.