about 3 years ago - SLG-Dennis - Direct link
You need to remove the old savegame after you change that and start a new one.
Also note that singleplayer only supports a size of up to 100x100 (from ingame, more will crash the 32-bit server) and on a dedicated server of up to 200x200 (more will maybe not crash depending on the power of your server / pc, but can cause issues and hence doesn't receive support).