Can't copy + paste correctly on iOS 8
I downloaded iOS 8 to my iPhone 4s yesterday, and I've now realised that I can't copy and paste texts correctly. For example; when I write a text in Notes, marks it all and presses copy and then goes to Instagram and pastes it - an old text that I used yesterday shows up instead of the newly copied one. And when I copy the same text in Notes and pastes it into a iMessage another old text (a link in this case) from yesterday pastes.
The strangest part is that sometimes, if I mark word by word (til the entire text is marked) and then presses copy and pastes it into Instagram - it works. But I did this just now, and deleted the text and tried to paste it into Instagram again - then the old text from yesterday showed again, even though I, one minute earlier, was able to paste in the new, copied text!
Does anyone know how to solve this, or should I go back to iOS 7? Because I've heard that iOS 8 aren't really optimized for 4s' ...
iPhone 4S, iOS 7.1.2