how to practice previous keys which have reached lower confidence level

[Jay]

Since I started practising keys had confidence level above 0.98, then eventually new keys were added which affected other keys since the new key will be repeated more often in all new lessons until you reach a confidence level of 1. 

During this lesson, I tend to focus on the new keys and I end up making more errors in other keys, but now the colour has become red for a couple of keys and there is no option to go back and practice those keys. The lessons still focus on new keys, then those with lower confidence levels. 

It would be nice to have an option where I can adjust which key I want to practice to increase confidence level for those red keys.