How to get better sound on your videos?

I'm filming a YouTube video but I can barely hear anything because it's on my iPhone
Is there a way to make the sound better?

Basically go to Sony Vegas and insert your video, then delete the video and keep audio. Save the audio as a MP4 file separately, then use Audacity to load your audio and use YouTube guides on how to improve your audio using Audacity. There ya go! I use Audacity myself.

Check out my youtube channel and subscribe? Youtube.com/dagamertechy

Sound can make or break a film, so pay special attention to it
ALWAYS try to get 15 SECONDS of just sound per each environment - this will come in handy during editing
What you hear in your headphones (if applicable) is what you're recording
Plug-in mics are better than built-in mics
Omni-directional mics favor the loudest sounds
Point uni-directional mics directly at sound source
Clip-on mics are best for interviews
Protect mics against wind noise
Consider acoustics and mitigate sounds as best you can (eg: turn-off music in background)
Always test your sound.