The file will be opened as view only
I have an Amazon Kindle Fire HD 10. I use it to read pdf documents, and I used to edit, highlight, and write on them with no problem. Then I used to save them in my dropbox and I was able to see my comments and edition in different devices. Some months ago this changed. Whenever I open a pdf document in my Kindle I have this warning: "The file will be opened as view only" so when I edit the pdf I just cannot save it. I don't understand how that happened or why. I tried uninstalling dropbox and adobe reader, I have also restarted the device. I noticed this only happens in my kindle, I can edit the documents and open them from my dropbox in other devices such as my laptop with no problem. Can anybody help me, please?