Trying to open pdf's but they are now password protected, why and how do I change this

Question

why
did this happen and how do i open pdfs without needing a password that i dont have

Answer 1

When you share an iCloud account any synced data such as contacts is merged.  Also, any action you take on one device (such as deleting contacts) is synced to the other.  (That's what iCloud does; it syncs changes across your devices so they maintain consistent data.)  Unfortunately, you contacts are no longer in iCloud.  Your only option is to try restoring your phone to your last backup, which may recover your contacts.
To sort out your iCloud issue, one of the phones need to be migrated to a separate account.  On the phone that will be moving, go to Settings>iCloud, scroll to the bottom and tap Delete Account.  (This will only delete the account from this phone, not from iCloud.  The phone that will be keeping the account will not be effected by this.)  When prompted about what to do with the iCloud data, be sure to select Keep On My iPhone.  Next, set up a new iCloud account using a different Apple ID (if you don't have one, tap Get a Free Apple ID at the bottom).  Then turn iCloud data syncing for contacts, etc. back to On, and when prompted about merging with iCloud, choose Merge.  This will upload the data to the new account.
Finally, to un-merge the data you will then have to go to icloud.com on your computer and sign into each iCloud account separately and manually delete the data you don't want (i.e., deleting your daughter's data from your account, and vice versa).
Another thing to avoid is using the same ID on both phones for iMessage and FaceTime.  If you do, you'll end up getting each other's text messages and FaceTime calls.  If you're doing this, on one of the phones go to Settings>Messages>Send & Receive, tap the ID, sign out, then sign back in with a different ID (such as your iCloud ID).  Do the same thing in Settings>FaceTime.