I would like to know how I can change the color of the blue selection in the upper part of this elements. You can see that the head includes a title and three other options. This menu is selected in blue, how do i change the color in red?
The selection indicator color of an object depends on the layer where the object is. The color can be changed in Layer options. You find it for ex. in the panel menu of the Layer's panel. Create a new layer there and you can input directly the wanted selection color. An example:
Layer 1 has the default color (=blue). I created Layer 2 and set its color to red.
When you draw a new item select at first a layer for it in the Layers panel. I drew a path to both of my layers. Both paths are selected:
Layer 2 has a rectangle and Layer 1 has an ellipse.
If you move an object to another layer (=drag it in the Layers panel) its selection indication color updates. Now both paths are in Layer 1: