To sync your transactions to your other devices running Pocket Cash, you will need an iCloud account. With an iCloud account, you will simply just need to turn on “Use iCloud to sync and store data” in the application preferences.
Please note that the first device which switches on iCloud sync will initially move the database from the device to the iCloud servers. This database becomes the ‘master copy’ so to speak, and then gets pushed out to your other devices from the cloud. Consequently, all devices will have the same data and be kept in sync. (Please ensure that the device with the correct data is the one which turns on iCloud sync in Pocket Cash first, to ensure it becomes the master copy. As turning on the device with blank database will override the current data that you actually want to be on the cloud.)
Your data should sync over within a few seconds to a few minutes depending on how busy the iCloud servers are. If the data still has not synced, please restart both your devices, this usually should help solve any delays and iCloud issues.