you could try changing the speakers,but you have to shop around for one that's louder, am not sure where, or, you could try getting louder and safe earphones something like Beats by Dre will work fine for you.Then you will need a volume boosting app, you could try
volume+ or
speaker booster try one of those and see what works...then you will also need an equalizer to have some quality sound coming into your ears shop for these on google play you will get something interesting and good enough.
The problem might also be that your previous phone had a very high volume that it damaged your ears, or you used to listen to music at a very high volume and that might also have damaged your ears.Hope this helps.