I would suggest two things. First, go into All Settings/General and scroll down to Sounds and check that your Alarms volume is up there as well as in the app itself. Second, go into your alarms in the app and make sure that you have an actual sound chosen for each alarm. One of the alarm "sounds" in that app is actually called silent... because it's silent!
If neither of those things work, you can try archiving the app and then unarchiving for a clean reinstall.
Hopefully one of these solves your issue.
can you please make sure to update to the latest version.
To do so head to "Apps"
-tap on a menu icon in the bottom left corner
-tap on "Check for Updates"
Once the list with updates appear, tap on "Update all".
I did check for updates but none was available. On the screen shot of the alarm it shows a "silent" mode, but that does not appear in my setting choices.