To change the units, Go to File -> Prepare-> Model Properties and then from the model properties windows, click on Change under units. There are 3 ways you can change the units in which 2 will be used for changing the default setting.
Tag: change units in creo drawing
Scaling the whole model in Pro E / Creo
In Pro E versions: Go to Edit → Scale model from the Main menu at the top.
In Creo versions: Go to Model tab and in the Operations group, expand the arrow and select Scale model.