Bugs
So pissed up by zotero. Heard a lot about them, thought of trying. Firstly I tried on tablet, there was no option of highlighting. Then i tried to login with same password on my iphone. It failed. Tried to forget password, new password working fine on browser but not on app. After half an hour finally same password worked. Later I realized on iphone app there is an option for highlights but cannot erase those highlights. Seriously?
Upgrade Storage
You can both create and delete highlights on any device. If you're confused by something, provide some screenshots of what you're looking at and we can help.