Edit Footprints
Edit Footprint in Library
When you found a Footprints(footprint) but it can not be satisfied for your design, you can edit it to be your personal PCB footprint.
Via Library > Footprint > Search Component/Personal/LCSC/System > Select footprint > Edit
You can edit the pad size, shape outlines, etc. when you finish and save, it will be saved to your personal libraries "Created" and become your personal libraries. And you can add a tag for your Footprint when you save it: 
Modify the saved Footprint tag at "Library" part list. 
Edit Footprint in PCB
If you want to edit a package(footprint) in the PCB, you can use the Ungroup/Group function same as the schematic.
On the PCB Tools palette there is the Group/Ungroup Symbol… button.
This tool is for you to quickly create or edit library symbols.
Select a footprint
Click the Group/Ungroup Symbol… button Up to this point you have a collection of separate pads, a drawn silk layer tracks and some text that are all