if you are using online any edit of a tax form will be an override and thus you won't be able to e-file and Turbotax's accuracy guarantee is void.
depending on the version you using, you may be able to use support to aid in finding the source for the entry
5am-5pm Pacific Time (8-8 Eastern) Monday - Friday
https://support.turbotax.intuit.com/contact
800-446-8848
otherwise, since an entry here can come from many different worksheets, you need to go through them one by one until you can identify the source.
