If you want to get rid of adds, plug your device on your computer, open the .kobo directory, search for the affiliate.conf file and open it with the notepad : you'll find that text
change the word "fnac" (in France for exemple) for "none" (or any other word of your choice) and save the changes before disconnecting properly your reader and then you'll get the option in the parameters (light, sleeping mode and power) to choose "use a screensaver=> display the current reading book cover" (at least it's what that is sayed in the French version) so that if you check the box, your cover will be displayed and uncheck you'll get the sleeping face.
I must admit that I learned how to make that here at mobileread when, after an update, I had no longer the option to display the cover of the book on my Touch
It worked with the kobo Touch, and now, after updating to 2.8.1 with my glow, it worked well too
