1.Log into Salesforce as Administion
2.Setup | Create | Objects | Incident
3.Page Layouts | Edit the Layout ( This should be the layout assigned to user’s profile with which you are testing )
4.Add Edit Button (Add it in Standard Button Section)
Once you do this refresh your Salesforce1 app on Mobile phone > Settings >Advanced > Clear Cached data > Validate the issue.
You can add this to all other layouts on which you do not see buttons.