There is "Describe the Partnership" screen (see below) during your K-1 entry. Select the "I have passive activity losses carried over from last year" line, and the following screens will have boxes for your carryovers from 2018.

If you have QBI loss carryforward, you will need to indicate that you have carryovers from the prior year, and manually enter that those carryforward amounts.   In TurboTax Online, you do this in the section Income>>Other Business Situations>> Net Operating Loss/QBI Carryforward Loss.  In TurboTax Download/CD versions, you use the path Income>>Less Common Business Situations>>Net Operating Loss/QBI Carryforward Loss.

Here is that "Describe the Partnership" screen where you indicate that you have passive loss carryforwards: