Unfortunately at this time our app technology does not allow you to set your timer as "Always On". All Apple Watches fall asleep after 15 seconds. Luckily, your timer will continue to run in the background even if your watch is asleep. When your timer is up, the watch will vibrate, ding and bring a visual alert up on the watch face.
We continue to work on making updates to our app to make it as useful and user-friendly as possible. If you have any additional questions, please contact firstname.lastname@example.org.