First time user for TurboTax doing 2018 LLC return. My opening capital account balance doesn't match my book balance. how/where to is make the adjustment?

What kind of return are you preparing?

In a partnership return in TurboTax Business, you can adjust the opening capital account balance for each partner by following these steps:

1. While in your return click Business Info > Partner/Member Information.
2. On the Partner Summary screen, click Edit next to the first partner.
3. Continue to the Partner Capital screen and make the adjustment in the box Last Year's Ending Capital Balance.
4. You can also make any other adjustments (contributions, distributions) and click Continue.
5. You will be returned to the Partner Summary to make adjustments to the other partner(s)' capital accounts.