Avidemux Forum

"Safe as default" saves 'Video Output' setting and 'Output Format' settings but does not save 'Audio Output' settings. It defaults to 'Copy' even when something else was selected when 'Save as default' method was invoked.

Mainly works as intended as neither presence nor particular properties of audio tracks can be taken for granted. One can help oneself with custom scripts to conveniently configure audio encoder and filters for specific use cases.