If you installed TimeTrex from the legacy MAC OSX installer (which was discontinued since Apple has exited the server market), unfortunately there is not an easy way to upgrade the PHP version. You would need to install a generic web service stack (ie: https://bitnami.com/stack/mapp
) then install TimeTrex from the .ZIP file so it uses that instead, and manually migrate your database over to it. It can be a quite involved and complex process even for experienced IT professionals.
Instead you may want to consider switching TimeTrex to a different operating system such as Windows or Linux that would be much easier to install/maintain, or alternatively if eligible you could always consider using our free cloud service: http://www.timetrex.com/download.php