When I first switched myout for an , I slept through all my alarms for a week. The reason? I wasn't sure. My alarms were set, but they just weren't waking me up. It wasn't until I woke up during one of the alarms (by chance), that I realized my iPhone's alarm volume was ridiculously low.
Here's why: iOS has two different volume controls - ringer volume, which controls the volume for the ringer, notifications and system alerts, and alarms; and media volume, which controls the in-app volume for games, music, and videos in additon to calls. Because your alarm volume is tied to your ringer volume, you could be inadvertently muting your alarm by changing it before you go to sleep.
Here are some steps you can take to make sure your alarm is loud enough to, well, wake you up:
Turn it up
To adjust the ringer volume - not the media volume - press the home button to go to the home screen. When you're on the home screen, use the volume control buttons to adjust the ringer volume. You'll know you're adjusting the ringer volume because the volume meter on your screen will be labeled "Ringer."
If the volume meter on your screen is labeled "Volume," and not "Ringer," you may have your phone set up to only adjust media volume via the volume buttons. To fix this, go to Settings and then Sounds. Under Ringer and Alerts, you'll see a toggle switch labeled Change with Buttons. Switch this toggle on to adjust your phone's ringer volume with the volume buttons.
Use your phone's silent switch
If you're sleeping through your alarm, it could be because you're turning your phone's ringer volume all the way down before you go to bed. Instead of using the volume buttons to make your phone silent, just use the silent switch (above the volume buttons) to turn your phone's ringer off. This will turn off your phone's ringer but leave your alarm intact.
Check your alarm
You can check how loud your alarm will be from the alarm settings screen. To do this, open up the Clock app and go to Alarm. Tap Edit in the upper left corner, and choose the alarm you want to check. Tap Sound and then tap the alarm tone you want to use.
The alarm will start playing at the current ringer volume , which is how loud your alarm will be, assuming you don't change the level later. To make it louder or quieter, just use the buttons to adjust the volume while the test alarm is playing.