Local to Scene button greyed out under Sprite2D image texture resource

Godot Version

4.2.2

Question

trying to make a health bar system similar to minecraft with multiple hearts representing the bar, and i wanna make the heart a scene to reuse, but i need to make the sprites for the heart local to scene so i can modify 1 heart without modifying the rest. the button is greyed out. help

edit: heres an image too if it helps