Master pdf editor is a "Cross-platform PDF and XPS Editor" that is free for non commercial use. Download from the following url
With this easy-to-use and cost efficient application you can create, edit, preview, encrypt, sign and print XPS and interactive PDF documents with just a few clicks. Our robust and rich set of features includes the full support of PDF and XPS files, import/export PDF pages into JPG, TIFF, PNG, or BMP formats, converting XPS into PDF and vice versa, and 128 bit encryption. You can also add various controls such as buttons, text fields, checkboxes and more, as well as implement event handlers for predefined user actions such as pressing, clicking, hovering, and scrolling. Powerful commenting tools like Sticky Note and Stamp, as well as enhanced editing capabilities packed in the StrikeOut, Underline, and Highlight functions will make your work easier than ever. And what about the system requirements? They are as low as possible: Microsoft Windows 2003, 2008, XP, Vista, 7, and 8 (32 and 64 bit), Linux x64/x32 and Mac OS X. No hardware restrictions at all, so you can use the program even on legacy PCs.
The linux version works very well on Ubuntu. So try it