Net capital losses are deductible, but only up to a maximum of $3,000 ($1,500 if married filing separately). Any capital losses you couldn't deduct this year can be carried forward and deducted on future tax returns. This is called a capital loss carryover.

If you transferred last year's return over, we automatically include the carryovers. However, it's always a good idea to keep a written record of your expected carryover amounts to compare against your return.  If you need to enter a carryover, type capital loss carryover into the search bar and use the Jump to capital loss carryover link to be taken directly to the entry screen.  Answer YES to the Did you have investment losses you could not claim in 2018?  question and continue through the screens.  

Thanks for the info, but why do I answer YES to the “Did you have investment losses you could not claim in 2018”. Because I did claim the $3000 in 2018.

Capital losses accumulate through the years.  By answering yes to “Did you have investment losses you could not claim in 2018”, you are saying that there were losses that have accumulated and been used since 2013, and this reflects the current status.  The carryforward for 2019 will reduce the -$3,000 that you used in 2018.