This first method uses the Audio Mixer's Fast Menu. Here are some differences between the two methods before we start the recipe:
Using this method does not require you to display Volume or Pan Automation (though you may), while the second method, in the There's more... section, does require it.
This method is used to adjust multiple keyframes only. The second method allows you to adjust either a single keyframe or multiple keyframes.
Set the Audio Mixer to the Automation (Auto) setting, rather than the Clip or Live setting.
Enable the Track Selector(s) for the track(s) on which you want to adjust keyframes.
This is an optional step: Mark In and Mark Out around a portion of one or more segments...