I found the answer, in case someone else needs to use:
first, in the gui, we have to save the handles in the guidata (in case someone is not familiar with gui data - help guidata)
handles.left_handle = left_handle; % store the wanted handle in the handles sturcture
handles.right_handle = right_handle; % store the wanted handle in the handles sturcture
guidata(figure_handle,handles) % save all the handles in the guidata of the figure
in the callback function we can easily set the current axes of the current figure to the handle that we want:
function Callback_function(hObject,~)
handles = guidata(hObject) % call all the handles that we saved
set(gcf,'CurrentAxes',handles.left_handle) % set the current axis of the current figure to the handle that we want
imshow(...) % show the image that we want
end