I don't have a fix for this but going directly through Control Panel -> Hardware and Sound -> Devices and Printers and managing from there is a good work around.
No, this aproach is not solve the problem. The buttons apears same as before.
I believe you are confusing the new "Metro" Settings menu with the legacy Control panel. Inside Control Panel, you can set the default printer as normal.
Please see attached image:

Thank you for your help, you’re very kind. I belive the GUI must be serve the users needs, and when they feel unconfortable theyself for an error, the support could not say them: this is the other or preferred way to do something.
The screenshot showing the worst case. Could not be click the buttons.
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