Why can I not set the 'Position' of the 'textbox' based on a specific axis?

I have a figure with an image, and I would like to create a textbox annotation and position it based on the figure's axes. I use the following code to achieve this:

   figure;imagesc 
   ax_sa = gca 
   hTextEnd = annotation('textbox', ... 
   'Position',[0.3 0.3 0.5 0.5],... 
   'FitBoxToText','on','String',' End','Color','g','FontSize',16,... 
   'FaceAlpha',1.0,'EdgeColor','w','BackgroundColor','w'); 
   set(hTextEnd,'Parent',ax_sa);

Why does MATLAB not consider the 'set' statement and position the textbox based on the axis?

Answer 1

[MathWorks Support Team]

The 'Parent' property of the annotation cannot be explicitly set. This property of the annotation is hidden and does not work the same way as other objects do.

Annotations are positioned based on the figure and cannot be positioned based on a specific axes.

More information about the 'Position' property can be found in the MATLAB Documentation link below:

https://www.mathworks.com/help/matlab/ref/matlab.graphics.shape.textbox-properties.html#d119e39559