How to boost the sound on a laptop for movies only?

I’ve noticed that the sound quality of any dvd I watch on my laptop is not the best. The sound will be so soft on some movies, you can barely hear it. The volume will be at full length on my laptop and inside the movie player.

However…the sound is just fine when surfing youtube and other video sites, so I don’t think it’s my laptop that’s causing the problem.

Any ideas on how to fix the sound for dvd’s on a laptop?

I am aware I can get external speakers, but I’m talking about when I’m traveling. No one wants to lug around heavy speakers when they travel.