Changing quotation marks

Is this a bug or do I need to set something in the preferences?

See it here:

It is an interesting example, just out of curiosity I did it, and it’s really strange that I changed your quotes, now what I did was “txt”" and put the two quotes in the same way, I had to delete the third quote after… even several quotes to leave the two quotes the same, this is a very peculiar mistake