That's true (the preceding post).
I would think it is possible that when you save multiple kml's as a
single kmz, GE is making some assumption (or failing to make some
assumption) as to where to set the initial "LookAt." You can try
setting the lookAt the same in all your kml's and then save as kmz and
see what happens, but the same problem might occur.
Your better bet, if there is no reason not to, would be to combine all
your kml's into one kml and deal with it, rather than dealing with 7
kml's and combining them.
You would then have 1 niced, portable kml as well.
Many people use languages like php to actually write their kml code
for them. You could do that, too, if there is any convenience in that
for you. It is very easy because kml is very simple, despite the
learning curve and a few limitations in its features.