If you added it from ToolBox then you should of had options for customization when you drag & dropped it in. Once in an Assembly you should be able to right click on a ToolBox component & select "Edit ToolBox Component" under the "Component" heading.
If it is a TooloBox component you should see a grey looking bolt in the Item Tree for the part. If not you will likely have to edit the geometry & sketches manually to suit your needs.
If you added it from ToolBox then you should of had options for customization when you drag & dropped it in. Once in an Assembly you should be able to right click on a ToolBox component & select "Edit ToolBox Component" under the "Component" heading.
If it is a TooloBox component you should see a grey looking bolt in the Item Tree for the part. If not you will likely have to edit the geometry & sketches manually to suit your needs.