If you would like to know how to change your world seed, or add in a custom seed follow the steps below.
Log into Multicraft and follow these steps:
1. Stop your server
2. Click Files
3. Click Config Files
4. Click Server Settings
5. Scroll down to the Level Seed field and enter in the seed you want
6. Click the save button
7. Return to the main panel page
8. Go to the world box and enter a world name (can be anything, ie: myworld) - You need to create a new world name (otherwise, it will load your old world)
9. Scroll down and click the save button
10. Start your server.