When you change the parent payment amount in a batch, the soft credit amount does not update automatically. This happens because soft credits are treated as separate payments in the batch, and they can be set for any value up to the full value of the parent payment.
Why soft credits do not update automatically
Soft credits are recorded as their own payments within the batch.
Soft credit values can be for a partial amount of the main payment, not always matching the full payment value.
What you need to do
If you change the parent payment amount after entering a soft credit, you also need to update the soft credit amount separately to make sure they stay aligned. The system will not change soft credit values automatically.