editing a page owned by a lower-righted user makes me owner

hi. i have a small question. i got some users at level 6, who all should be able to edit one page. i made this page with a user “low” at level 5. the problem is: when a level-6-user edits the page, he thereafter owns it. that does not happen with me (at level 9). is there any way of not having the ownership change? (The level-6-users don’t even the the owner-selectbox)