For 2014 mower’s software version the following limitation exists: once you enable the second “Hours 2” slot via the app on the RC/MC-model mower, the entire menu of “Inactive Times” become unavailable via the mower. You need to disable “Hours 2” via the app in order to regain control of it via the mower.
If your mower has 2015 or newer software version, there is no such limitation. You can always change “Inactive Times” via the mower, but only of “Hours 1”.
The second “Hours 2” window is only available via the app.