Do I need to create a new account in order to file quarterly taxes as a new sole proprietor business (July1)? I cannot access a 2019 Schedule C from my online account.

You do not need a 2019 program to make estimated payments ... you can use your account in the  2018 program to compute them OR  simply get the forms and fill them in manually  OR  just make payments online at www.irs.gov.

Scroll down to the bottom of the screen and Click on Add a state

This will take you back to the 2018 online tax return.  If you have filed the 2018 tax return do Not make any changes to the return that was filed.  Only access the estimated tax section and then print the estimated tax forms if needed.

1. With your tax return open, enter 1040-es in the Search box located in the upper right of the program screen.  Click on Jump to 1040-es
2. Answer No to the question,  Do you want to change your W-4 withholdings for 2018?
3. On the next screen, Review Your Estimates, select Review Now.
4. Proceed through the interview, answering questions about your 2019 filing status, income, deductions, etc.
5. Eventually, you'll come to the Print Vouchers screen; answer Yes and we'll include your 2019 1040-ES payment vouchers when you print a copy of your return later.

You do not "file" quarterly taxes. You "pay" them. You only "file" a tax return once a year. To pay your quarterly taxes to the IRS online just go to www.irs.gov/payments and do it there. ***PRINT*** ***YOUR*** ***RECEIPT*** when done. When dealing with the IRS, if it's not in writing on a physical piece of paper, then it flat out did not occur.

If your state also taxes personal income and you need to pay your state quarterly taxes, then that is a totally separate transaction between you and your state taxing authority. Not all states have the ability to pay your state quarterly taxes online. So you'll need to check with your state's tax website to see whatever payment methods may be available to you.

Both of the above answers are correct.

You will not be able to prepare a 2019 tax form like a 2019 schedule C yet because the 2019 software will not be released until late November.  You have to wait for the 2019 tax software and for the 2019 tax forms—which must be approved by the IRS. Follow the suggestions of Critter and Carl to make estimated 2019 payments. 

Thanks, all - good insights all around. I ended up getting a new QB service in order to access the small business services and estimate taxes, etc. I appreciate the community support forums as I find the provided online support too meager when I actually need help with something.