I am new about unity，I found that in the function named SetCharArray, like this:

I have a TextMeshPro object for output and i want to change its text. What i found is that the text is changing but not updating. The weird thing is that i can change it and it updates when it is on start but later on when i try to change it , it does change but do not update.
The TextMeshPro object is inside a canvas so i am using an TextMeshProUGUI. TextMeshPro cannot be used cause it does not allow me to drag and drop the object. Tried also delcaring it with get component at start but it gets worse and text dont even change therefore it dont update.