Capital Gains/Losses from previous tax years

This is my first time reporting crypto on my tax returns, though I traded them in previous years.

My capital gains CSV report for 2020 shows only the BTC I sold in 2020 (but bought earlier, in some cases). However, I have bought and sold BTC, ETH, LTC, and XRP in previous years and the loss/gains are not appearing in this 2020 report. I realize I may have made an error by failing to report some of these transactions in the past, but how can I correct for that now? Do I need to subscribe to the Tax Loss Harvesting platform to have access to generating reports from previous years?