Hi
Had the same problems as all of you here- had over 150 notes with password / logon information
for myself and a lot of my family members...(parents etc..)
Really had a big problem after installing IOS11.
Tryed to downgrade to IOS 10.3.3 but no luck after several attemps on different computers...
Luckily I had an backup from before I updated to IOS11- disabled automatic update on phone
so I didn't overwrite with a IOS11 backup..
Was desperate so I did desperate things....
Borrowed my wife's Iphone 6 (I have 6s) and she had luckily not upgraded to IOS11 yet - and managed to use
Itunes to set this phone up as mine.(used mine pre IOS11 backup on my wife's phone).
Managed then to access the "Safe Note" app and took screenshots of all of my notes and backed this up
in some "cloud" I have....
Then reinstalled my wife's software on her phone- and everything is ok !
So IF you have a pre IOS11 backup - try to get hold of a pre IOS11 phone and load the backup on this- then
save the notes as you like (pictures / screenshots).
If my wife didn't have this phone I really would think of the option to buy a second hand phone and to sell it again after.
Hopefully this is an idea which might help some of you out there.
Good luck.
Best regrads Ove