Each country uses different methods for calculating capital gains. In the USA the most common method is FIFO followed by the less-common LIFO. Canada uses ACB. UK uses Shared Pool and so on. Koinly supports FIFO, LIFO, ACB, Shared Pool, HIFO, and even less common variations that involve wash sales (such as the FIFO used in Ireland).
Koinly uses recommended settings for the Home country that you selected when signing up. If you are in doubt, you can contact your tax authorities and ask them which method you should use to calculate your capital gains and change it on the Settings page.