If you want to set a default image behavior/action...
In Windows Live Writer, insert the first image...
Apply all the changes [customizations] you want to the image [drop shadow, water mark, size, etc.].
Once you've done this, [under Picture Tools, FORMAT] choose SET TO DEFAULT.
With that blog account, from that point on [even when you restart the
application], all images added to the post will be treated the same way. This is now the DEFAULT action for inserting images for that blog.
If you need to clear this action [under Picture Tools, FORMAT] choose REVERT TO ORIGINAL.
I hope this helps...
Until next time,