I don’t have this problem, in Scapple on MacOS. Can you add some screenshots?
Is it possible that when you’re adding the link you don’t have the whole title of the note selected but just ‘My tot’ and that’s the part of the title that the link is being assigned to?
Double-Click to add a new note.
Give the note a title, e.g. My totally original notes!
Select the whole title text with cmd-A, then select from menu, Edit, Add Link:
Paste your link and click OK.
However, if you just select My tot instead of the entire title, the link will only be associated with that part of it:
Following on from the conversation below. The problem is with Notepad, not Scapple:
Notepad uses a Windows-specific end of line character which combines a carriage return with a line feed. Whereas non-Windows apps will just use one or the other. So, when Scapple sees \r\n it doesn't recognise it as an EOL character. It's expecting either \r or \n. As a result, it sees the link as youtube.comMy and the word example as an extra piece of text.