You are welcome. Even though most users will be satisfied by the default values, it is really nice that we have such a high level of configurability available now compared to the less flexible Arduino IDE 1.x application.
Unfortunately the ability to modify individual parameters of installed themes is not yet provided by the free open source Eclipse Theia IDE framework Arduino IDE is built on:
If you have a GitHub account, you can subscribe to that issue to get notifications of any new developments related to this subject.
You might be interested in this information shared by a forum member about installing 3rd party themes in Arduino IDE 2.x and even creating your own custom themes: