To see the rewards hostory online you can do the following:
Figure out your staking address:
Open https://cardanoscan.io/ and search by one of the receiving addresses that you can find in your wallet. The staking address will be shown under Controlled Stake Key.
Show the history:
Open https://pooltool.io/address/STAKE_KEY_HERE by replacing STAKE_KEY_HERE with your staking address obtained in the previous step.
You’ll get a view with the rewards history for your staking address.