Hi @betofe_keyta ,
I hope you're doing well. The easiest way is to right click on the individual components and then select add 3D model. This is good for one off changes but is not what we recommend as best practice. It's not the best way because it only works for the current design only and you'll have to do it for each individual component.
The best way to do it is to go into the library and assign the 3d model to the component there. Once that's done then you can just do a library update and all instances of the component will now have the 3D model. Additionally this will work across all of your designs.
Let me know if there's anything else I can do for you.
Best Regards,

Jorge Garcia
Product Support Specialist for Fusion 360 and EAGLE
Kudos are much appreciated if the information I have shared is helpful to you and/or others.
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