Using format paintbrush (copy format) between windows

I am able to copy formatting (font in my case) within a document, but if I copy a format and switch to a different window and attempt to apply the saved formatting to the text in the second document, nothing happens. Am I doing something wrong? I’m hoping to get a satisfactory answer that involves the use of the paintbrush.

Copy a text sample from the original file, paste it on the destination file, then select it, press the Clone Formatting tool (the paintbrush), press Ctrl+Z to undo the previous pasting, and select the text to which you want to apply the format. Done.

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