If you do choose to work with a company that makes its self-publishers sign book publishing contract terms, you should definitely have a lawyer look it over before you sign it.
You sign the wrong contract, you might end up losing the rights and royalties to a potential audiobook, the eBook, or even future edition updates.
When you publish a book, you don't have to make any compromises.
As the publisher, you should retain all the rights to your work and maintain control over it.
If you work with a publishing company that is asking you to sign a contract, be wary.
Here is a Free Video Self-Publishing Resource where you can learn more about Publishing Contracts.