user description displayed on profiles but cannot be edited

I have a field (profile-aboutme-contents) displayed on profiles but hidden in edit mode and Profile Manager 7.4.1 settings

I have found a solution to hide it on the profiles but I have around 300 users who have entered their description in this field and I don't want to loose it.

Do you have an idea? tks!

PS: i use Elgg 1.8.8