as lumineers are very thin ceraminc veneers, it is extremely difficult to make the changes on them after they have been cemented in your mouth. the only solution if you are not happy with the over all results is to redo them. but before the next set of veneers are placed please ask your dentist
to first place temporaries which will be the replica of your lumineers. once you are happy with the results of the temporaries then only get the finals fixed.