When i add a custom map do i leave the level.seed and the world.size alone? Or should i just remove what evers in there because ive put the new map link in the cfg and when i start the server it goes back to the old map before and i'm also removeing the old map files.

Yes, leave seed and worldsize blank. Also, you need to upload your custom map to DropBox

Merged post

How to run a custom map

thank you!