Currently, the settings within Configuration>Sequence>Key Initial Values are only applied to new clips that you drop onto your timeline.
It would be great if you could add a modifier key that would allow you to right click on a clip on your timeline, and quickly apply these Key Initial Values to this clip, rather than manually adding opacity keyframe, copy and pasting or using presets.
Another nice addition would be to modify existing fade in/out values of a clip on your timeline with a single click