KB: 複数行のテキストを文字列にコピー

Solution Details

There is no format manipulation of the copied text when you paste it into Altium.   The individual lines will be pasted as they had been copied.
 
Try pasting the text into a text editing program (like notepad or Microsoft Word) then you can get it into one line as desired.  Copy it from the text editing software, then paste it in the PCB or a Text Frame.