I managed this problem and many duplicates bugs :
* Bug #31864
* Bug #38149
* Bug #41303
* Bug #41304
* Bug #41402
So i resume here the problem.
When you use Gnome-Cups-Manager to mark a printer as default user, or when you change some parameters (like PageSize), modifications are saved in ~/.cups/lpoptions . This comportement is ok.
But this user configuration file is not used by gnome-cups-manager so user's parameters like default printer or user default parameters are not used.
STEP TO REPRODUCE THE BUG:
add a new local printer (even if you don't have one)
change settings (like paper format A4/A5/A3 ...)
view ~/.cups/lpoptions ... your changes are well saved.
go to printer settings and you can see that your changes are lost
> ORIGINAL DESCRIPTION
>If I set my printer (HP Deskjet 6540 with hplip) to fast >draft mode it will not work. It still prints in normal mode.
>If I look at the web frontend for cups the settings didn't >change.
>If I change the settings directly in the web frontend it >works as desired.