My wife and I are filing jointly. When I enter a Form 1099-B, it doesn't ask whether the Form is for me or my wife. Isn't that important to identify?

[macuser_22]

No.  On a joint return it is joint income.     Only W-2's and 1099-R's ask that because Social Security/Medicare has individual limits and retirement income is per person.

[fanfare]

any carryover losses on Schedule D  will go  with the spouse who owns the account.

It's up to you to keep records about that.