This has been mentioned before, although simply swapping out the quotation terms with the default invoice terms was not desirable in all cases. We have some users who attach specific terms on the quotation that need to be carried through to the invoice. We are reluctant to change this as I can’t see it being useful to all users.
What you can do instead is when you convert, select the option to tweak first, you can then click the highlighted link to import the default invoice terms.
