How to Normalize volume of Mp3 file

Default volume for normalization is 89.0 dB. You can see it on status line. You can change it to another values then 89.0 dB at Options-Normalization-Target Volume.

It is always good to make undo track volume, before going with another target volume if files are already normalized.

Zortam is using mp3gain (http://mp3gain.sourceforge.net/faq.php) for the normalization process.