You went into this folder:
/Library/Application Support/
you need to go into this folder:
~/Library/Application Support/
I tried, but I’m probably doing something wrong. I am totally confused now. Maybe I should download SketchUp again and see it that changes anything…
You are looking in the right place, for where SketchUp usually saves components. But, I think you have been saving the components into another location, and so they don’t show up in the Components panel.
Mike was right about the replace text being missing because you are trying to convert a group to a component.
Not sure why the object had the yellow lines around it, but you could open Styles, and Edit the one you are using, to see if you have yellow set for the locked state.
Aha! You should not make a group before you make it into a component. Just component right away. I get it now! Thank you so much! 
Making a group before you make it a component is a waste of time.
At least now I know how to save a component, so I simply have to change it so the frame disappear so that’s nice! I have many to change though. Phu! 
Just posting a screenshot doesn’t really help us sort out the problem.
Attach the model so we can check it.
The two most likely options are you have stray geometry within each component a long way from the main part or you have somehow set the component axes/origin a long way from the geometry.
I’m not sure where to start with your issues. Unfortunately I don’t have time to delve very far just now, but one of the major things is your model is absolutely full of hidden stray geometry. This is causing your huge bounding boxes.
Go to View Menu and turn on hidden geometry.
Your model is also a long way from the origin, which may well be the cause of the other thread you just started, but I haven’t looked at that.
Oh dear! 
Thank you so much! I don’t know where it comes from, I don’t recognize it. Maybe it’s in my template.
I guess I just have to explode all components in this document and delete the weird parts. But then I have to fix all components as they are saved in files om my computer.
Should I always choose “parallel projection” and “hidden geometry” when I daw in 2D? In 3D as well?
Because I don’t really understand what parallel projection and hidden geometry means.
You should be modeling with the camera set to Perspective.
Both when drawing in 2D and in 3D? Then how do I know if I have made some misstake so it becomes/looks weird again?
You have to look at the model. Pay attention to it when you are modeling and don’t let it get out of hand like this one has.
Obviously… just afraid of making misstakes again.
