The short answer is, change the name of your app. The standard for trademark infringement is confusing similarity. If the marks are identical (which you say is the case, both being XYZ) and if your goods are the same type as theirs and as is recited in their trademark registration, i.e., computer software, then your usage is confusingly similar and you are infringing their trademark. Put another way, someone going to an app store and seeing two apps with the same name has a reasonable basis to assume that they are being produced by the same company despite any differences in coloration, type font, etc.
Answered on Feb 24th, 2014 at 4:35 PM