Why is my alarm volume changing to my headphone volume?

When I go to bed, I set my alarm volume to a very low setting. (I don’t want to wake my husband.)

I then listen to my sleep podcast with earbuds at a higher volume and fall asleep while listening.

(At some point during the night, I take my buds out of my ears)

When the alarm goes off, the alarm volume has changed to the higher volume level and wakes up my very cranky husband.

Why are there independent volume settings in my alarm application if they are automatically changed when I use another app?

How can I fix this?