ADE - Highlights never saved

Hello,

For university, I easily use highlights in ADE. The matter is that nothing is saved when I close it and reopen it. Hours ok reading and work is lost.... 

I've learnerd that highlights are not visible on more than 1 computer, but what about the same computer? I now use only one of my computers for that reason! Why do I lose everything??

Before trusting ADE and reading for hours, I've made a test yesterday with few highlights. I closed my book and reopened it and everything was fine. And then, today, everything, every highlight, disappeared. I've tried to restart my computer 3 times and can't understand what's happening. 

Thank you for helping me.