It's probably all those "trigger once" conditions, you are using them wrong. Remove them and use Timer behavior when you need to schedule something.
Also, your event #18 runs on every tick, and you have "Wait 1.5" in it, which means that everything else in this event will run many times with a 1.5s delay. And will continue running for 1.5s even after the "doorknob" sound stops playing. Don't use "wait" in non-triggered events.
The whole thing can be done in the same event where you play the sound:
Audio play doorknob sound
Wait 1.5s
Dialogue set visible
Dialogue typewriter text ....
Wait 2.5s
Dialogue typewriter another text ....