Density of the Text

I try to put a merge component. It didn't make any difference except that I notice that the density of the color of the letter, change depending of the backgroud. If I set my text on a part of the picture which has dark and light spot, the text color density increase for the part which are on the dark spot and decrease elsewere.an someone explain me. I simply try to understand how this alpha channel works.
Thank
David

So I find out how to attach a image.
Could some one explain what happen here to understand what I am doing?
Thank you very much
David

according to the picture you have set the color in the layout tab to a solid black (rgb=0, a=1) and in the shading tab the color of the text is set to a color with no alpha (a=0)

I suggest viewing the text tutorials.

Thank you for your kind reply. I solve this small problem
I already saw those tutorials a lot of time but I am a Newbe and a lot of things still go over my head. But I will make it.
Thank
David