Airdrop cost basis wrong

Describe the problem:
I claimed the DYDX airdrop on the first day it became available. The cost basis Koinly shows is far too low. And affects my subsequent capital gain when I sold it. My notes at the time and also other data shows a much higher cost basis. There is a similar problem with ENS airdrop.
How can this be changed?

Which exchange/wallet is this regarding?
Metamask

How did you import data into this wallet?
API

What have you tried to fix this so far?
Editting the ‘Net Worth’ of the airdrop transaction, but it is ignored.