If you have a loss on Schedule C, the interview screen to indicate that All investment is at risk, or that Some investment is not at risk, is at the end of the Q&A for Schedule C or in the Business Income section of the program.
If everything that has been invested in the company is from your own funds, and therefore any loss by the company comes out of your own pocket (and is not covered for you by someone else), then it is likely that all of the investment is at risk.
See the IRS Instructions for Schedule C for more information.
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