everything has a blue outline

Hi, I am pretty new to Sketch Up, sorry if this is an obvious issue. I was working on a project and all of the sudden all the models in the project have a blue outline, even if they are not selected. Im not sure what I may have done, or how to get back to the normal look of things, any help would be much appreciated! Thanks

Have you changed the edge color in the style settings?

Open the Entity panel [menu] Window > Entity info
Try Shift + Command + A to be sure not have anything selected.
Otherwise share the model here.