The dimensions of parts created in ECAD and imported by Creo Parametric are not parametric, and you cannot modify them. However, you can go into the Sketcher mode and add dimensions by redefining the part base geometry feature. To maintain maximum flexibility during the design process, you can create your board outlines and components in Creo Parametric.

After you export parts created in Creo Parametric through ECAD, you lose parametric associativity permanently. If you import them back into Creo Parametric later, the outline is not updated.