Is there anyway of editing the sound files to be louder and clearer?

[ARIA]

Even if I had to go in one by one on the sounds, is there a way of editing them? Its cool if there's not. Just curious. :3

If anyone knows, tell me that'd be of help!

Thank you! :D

 

[Kiyoteru]

In Audacity, you can set up chains that can batch process a whole folder of audio. You can make them by going to File > Edit Chains and choosing which effects/settings you want to do.
You may be interested in normalization (which will amplify/quiet all the audio to the same level) and EQ.
(However... this processing is a little bit pointless for UTAU. Resamplers already normalize the audio anyway, and EQ is best applied during mixing.)