Soung is known to frequent the area around the Royal Alexandra Hospital (RAH), along with local parks.
Sergeant Johnny Mullan from Paisley Police Station said: “By reviewing CCTV footage we know that Soung was in the Neilston Road area on Sunday morning. I would appeal to anyone who saw her, perhaps on the bus or after she got off the bus, to get in touch with us.
“She appears to have changed clothing from the pink hoody to a green jacket. Anyone who has seen Soung, or a person matching her description in or around the Paisley area, is asked to report this sighting so that we can investigate.”
Soung is described as being of slight build, around 4ft 11ins tall and wearing black leggings, black socks and black sandals.
Anyone with information is asked to call Police Scotland on 101 and quote incident number 1511 of 22 August.