Can't select objects in most of the parts of my prezi

I've opened my prezi to edit it after a while ( http://prezi.com/wnqzilbsrvd-/algoritmo-paralisis-braquial-obstetrica-pbo/) When I try to edit some bubbles and texts I amb not able to make click on them, like there did not exist, so I can't edit them.

What can I do?