In the case of incorrectly imported timestamps, you can adjust the time either individually or in bulk. 

For the individual adjustment select the trade in 'Enter Coins' and press 'Edit'. Then you can adjust the time by sliding the bars.

For Bulk Editing please select the 'Bulk Edit/Delete' Button and under Bulk Edit select 'Adjust Trade Time'. Here you can choose which trades - sorted by exchanges, trade groups, dates etc - should be adjusted by which amount of time.