>After a while, Send to OneNote always come back as the default printer. I am use to only click on Print to get the result on the printer. This is kind of irritating. I cannot associate it to specific reboots or something like that. But, there is something which keeps making that changing my default printer settings at random occasions. I would really like to know how to shut it down completely?

What's probably happening is that Windows thinks the printer you want to be the default is off-line, so it's falling back to the most recent one that appears to be on-line.

Probably the best solution is to make sure you have a reliable connection to the printer. With a network printer usually the most reliable way to connect is to give it a static IP address, then on your computer set up a local port to that IP. This avoids any DNS issues with network printers not registering themselves properly.

Most network printer driver installers assume the printer is getting its address via DHCP and so it references the printer by its host name. This requires the DNS server to register that hostname to that IP each time the printer boots or reconnects. If the printer's IP address changes (via DHCP) but your workstation is still caching the old value, the printer will appear to be off-line. Assuming DNS is actually OK you can fix that problem at your workstation by manually issuing

ipconfig /flushdns

You can also check https://social.technet.microsoft.com/Forums/windows/en-US/316fd408-4957-43b1-92e3-8dda96dcdded/default-printer-keeps-changing?forum=w7itprogeneral for other ideas.