I have filled my 2024 taxes today, however I now need to complete my 2023 taxes on Turbo Tax. Where can I go to complete this?

You cannot change the tax year.   The current online program is for 2024 only.   Only a 2024 return can be prepared online and only a 2024 return can be e-filed.

Online preparation and e-filing for 2021, 2022, and  2023 is permanently closed.

Note:  The desktop software you need to prepare the prior year return must be installed/downloaded to a full PC or Mac.  It cannot be used on a mobile device.

To file a return for a prior tax year

 If you need to prepare a return for 2021, 2022, or 2023  you can purchase and download desktop software to do it, then print, sign,  and mail the return(s)

https://turbotax.intuit.com/personal-taxes/past-years-products/

You may also want to explore purchasing the software from various retailers such as Amazon, Costco, Best Buy, Walmart, Sam’s, etc.

Remember to prepare your state return as well—if you live in a state that has a state income tax.

https://ttlc.intuit.com/turbotax-support/en-us/help-article/state-taxes/contact-state-department-revenue/L9qVToi02_US_en_US?uid=m6e06um0

When you mail a tax return, you need to attach any documents showing tax withheld, such as your W-2’s or any 1099’s.  Use a mailing service that will track it, such as certified mail so you will know the IRS/state received the return.