I'm not certain about your use of the term "qualified joint venture." You and your spouse do not file your tax return "as a qualified joint venture." You file your tax return as married filing jointly. If you have an business that you own jointly, you can choose to treat the business as a qualified joint venture, provided that the business is not an LLC or a corporation.
You don't actually tell TurboTax that your business is a qualified joint venture. When you choose to treat the business as a qualified joint venture you report it on your tax return as two separate businesses, one owned by each of you. You split all the income and expenses according to whatever percentage of ownership you agreed on, and each of the two businesses reports its share.
See the following link on the IRS web site for more details.
https://www.irs.gov/businesses/small-businesses-self-employed/election-for-married-couples-unincorpo...
(When you first start to enter a business in a joint return in TurboTax, it will ask who owns the business. One of the choices is "Both of Us." But if you select that, it will just tell you to go back and enter two separate businesses, as I described above.)
