All V2 rewards were migrated for you to the V3 Strong Pool. They are only referenced in V2. You can use your wallet address and check here:
https://strongblock.com/docs/V2-migrated-rewards-12-5-2020.pdf
Please provide your wallet address, as well as a screenshot of the App with your wallet connected. That way we will be able to determine what you still have mined that you need to migrate.
For migration from V2 (legacy) to V3, you must make sure that you have completely unsignaled in V2; if you do not, you will see very high gas prices when you try to migrate. This is because the migration will not actually complete. You should also make sure that gas is relatively low (check at ethgasstation.info) prior to migrating.
-
Unmine all signals
-
Press the migrate button
-
Follow the steps as indicated (there are several)
-
Your V2 STRONGER will then be migrated into the V3 Strong Pool.