The basic personal deduction is automatically applied to your return if you qualify. Did you immigrate to or emigrate from Canada in the tax year? That might be affecting the calculation of the personal amount.
You've indicated that you're using our TurboTax Live Assist & Review edition. Why not give us a call and walk through your return with one of our tax experts to see what's going wrong? Here's how to reach an expert:
https://turbotax.community.intuit.ca/replies/3456106