Q: date and time default to CST

my ipad calendar defaults date and time to cst.  I have time zone override set to est.   If a sender sends me a calendar appt it shows up as cat and eat on my iPad calemdar.  I am using an exchange server for my email.  Anyone else have this same issue.  I have to go into the date open it change the time to est change the ttime zone in the calendar app to est despite the fact the over ride is already set to est.