How to change PlannerItems font size

My Planner has all items with a fixed font size.
As part of the user options, I want to change that font size, but I can not get it done in realtime.
Initially, I configure the fixed font with, for example:
  PlannerD.Font.Size := 8;
  PlannerD.DefaultItem.Font.Size := 8;
  PlannerD.Header.Font.Size := 8;

Then, If the user changes this option, I do the same as above with the new font size.
I can see the header with the new font changed, but not with all the items in the planner.

Is it possible to do so in real time.
If I unload the planner and load it again with the new font size, it is changed accordingly

This is by design. Planer.DefaultItem.Font is used when a new PlannerItem is created but after creation, the PlannerItem is using PlannerItem.Font and this is to ensure that each item can have a different font. If you want to globally change the item font's after creation, you'd need to loop through all the Planner's Items collection and set Planner.Items[x].Font.Assign(Panner.DefaultItem.Font);