How do I change my spawn radius? I changed it to 20000 but it still spawns me at 0,0.

Sorry for the delay.

Are you using Adventure mode?
That mode forces the spawn to the world spawn position.

From the config file:

#The number of blocks outward from the world spawn coordinates that a player spawns in when first joining a server or when dying without a personal spawnpoint. Has no effect on servers where the default game mode is Adventure.