Having problems setting, and retaining, the Updater Proxy in the Notepad++ UI?
Then resort to the command line. Open a cmd prompt, with administrator privileges.
At the prompt go to the Notepad++ updater directory, the following works for default installations:
cd C:\Program Files (x86)\Notepad++\updater
From here run this command:
This brings up the same dialog as the UI but this time the values you enter will be saved.