Bevel object

I’m completely new. Why can not I select the object in Bevel object
I choose one circle, and in Bevel shows another.
When only one circle in Bevel is nothing.

Well… That’s logicall.

When you have an object “A” you can choose an other object “B” to be used as a bevel.
It must be another object, or the loop would be infinite (A being bevel of A, which is bevel of A, which is bevel of A, etc…)

So… Yes, if you have only one object, nothing should be selectable in bevel, you must choose another object

++
Tricotou

If you want to create a donut that way, you don’t need to indicate a bevel object.
Just set Fill setting to Full instead of Half by default.
And then, increase Bevel Resolution and Bevel Depth.