Having hard time setting threshold for Particle Analysis

I am trying to analyze the bubble size in the attached picture. When I set my threshold then the picture does not see a lot of the bubbles. I am not sure what I am doing wrong. All i want to do is see the bubble size( area ) distribution,

Hi Bubble, welcome to the forum.
Your name is program, isn’t it?
How does your thresholded image look like?

Have you tried the local threshold functions in FIJI?