The date of birth must be changed under your Personal Information. The IRS does check last name, year of birth and the social security number for identification purposes. If you have not yet submitted the return you can make the change before you submit. You will not be able to change it on the signing page.
If you do send it through, you can wait for the IRS and see if they accept or reject the return. If they accept it you should wait for it to process and if they reject it you can change it immediately before you resubmit.