Problem with video scale

Hello,

previously, I had a small image target and I placed video texture on it. When I run the scene on my android device the video's scale seems okay and I'm able to scale it in with different sizes.

However, I Updated my image target to a bigger one and I placed the same video to cover part of the image target only, when I play the video on my mac the scale appears correct as I change it. But the problem now that it looks very big when I run it on my android device. I tried to change the scale and make it as small as possible but nothing changes!

I didn't change the script after updating the image target and I used "public bool KeepAspectRatio = true;" but nothing works as I want!

Please help me .