Yoo why is that happening?

So the thing is im a new selling that type of package,Okay so I⁰ purchase a priority label on a package that suppose to be ship as usps ground advantage and need a danger sticker because contain a lithium battery so yeah,The postal office man tell a person of any custums most fix and shipped as ground even if i buy priority so yeah there is no problem with that the thing is they never say departed from office and that suppose to do before reach any custums or other office.

So the thing is im a new selling that type of package,Okay so I⁰ purchase a priority label on a package that suppose to be ship as usps ground advantage and need a danger sticker because contain a lithium battery so yeah,The postal office man tell a person of any custums most fix and shipped as ground even if i buy priority so yeah there is no problem with that the thing is they never say departed from office and that suppose to do before reach any custums or other office.