Quotes can be tricky to edit as you need to follow the 'rules'
As long as the bit you want to quote is surrounded with a 'quote' and '/quote' you're good to go
Am I missing something?
I have a little button with the word quote beside it.
This opens to a new window and I type below the text I am quoting. (After the solid bracket ]after the last word [/quote] ).
If I want to delete some of the quote which is not relevant to my response, I go to the quote and delete the words I want to delete but never the opening and closing [/quote] .
I preview.
I post.
QED