Not able to write on PDF documents or on my Kindle books

The boox I have advertised itself as being able to write on pdf documents. This has not been possible. 2. The writing on my note is not aligned. It seems to keep running away and the letters do not form at the point of the pen.  3. I am not able to make annotations on my Kindle books and need help..There is no highlight function to make on this Boox device. I have the 12 colour option but it hasn't been useful at all