Your filed return will be pending and can not be changed. If your return is accepted you will get an email. If the return is rejected the e-mail will tell you what to correct and you can make changes before e-filing again. Amend to change an accepted return after you get your refund. Instructions below
https://ttlc.intuit.com/turbotax-support/en-us/help-article/tax-return/amend-federal-tax-return-current-year/L7eS6o1qh_US_en_US?uid=lqylnbrx