A problem with VOB file

I installed some softwares for cutting and joining dvd videos (super dvd cutter and joiner, ultra dvd cutter and joiner) they worked well but gave me a problem that I can’t understand at all. It happened this way: Before those softwares the sound level was high and it echoed in the hall around. after those softwares it reduced for VOB files only. all the rest formats have great sound level. can you please help me on this. How can i bring the level back where it was.