To do this, you will need:
- 1 controller/administrator/creator object (
obj_Hades
in my project)
- 1 global variable (
global.number
in my project)
The controller object (obj_Hades
) will basically serve for you to declare the global variable (global.number
).
Note that a sprite contains 3 images/frames:

In the controller object (obj_Hades):

Be careful to place the controller object to be initialized first (see lower left corner of image above).
In the object to have three different shapes:

Remember to set the image_speed
variable to 0, so that you don't run an animation.
Result:

Reference:
https://docs.yoyogames.com/source/dadiospice/002_reference/001_gml%20language%20overview/variables/global%20variables.html
If you have separated the images:

Just make use of IF'S
.
EDIT 1
Test done with your project:

I deleted the 3 objects and added them again. I realized that the ones you had placed in the room were different sizes, I don't know where you modified them, but apparently that was the cause of the problem.