Leaving Facades Unlocked means that they will be affected by any changes made to settings for the entire model such as Glazing Percentage, Glazing Specifications, Percentage Frame etc.
If you wish to lock a specific Façade or Surface into its current condition and prevent any future changes affecting these, uncheck the Selected surfaces unlocked box so that it will then read ‘Selected surfaces locked’. This prevents any subsequent actions (e.g. changes to other Facades) from making modifications to the condition of that Façade or that Surface, and its settings will remain in their current state.
You will notice that once you have unchecked this box to lock a Façade/Surface, the controls grey out and you will not be able to apply any settings until it is unlocked again. This prevents any changes being made to these Facades/Surfaces when adjustments are made to the model (eg. overall glazing percentage, specifications etc).