To Quote text from a post. Use mouse to highlight text to be quoted. You will then see a toolbar above the highlighted text which will include "Quote".
Hit that.
The Quote will then appear in the Reply box.
If you want to move the quoted text to a different post, highlight it in Reply box, (between and including [quote...] and [/quote] ) to put in clipboard, then copy the text to where you want to paste it.
Not so easy to explain in words, but hope that helps.
Note: I see there is also a "Copy Quote" item in the toolbar, but I have never tried that myself.
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