Mallsai is a somewhat tongue in cheek, somewhat derogatory, term used to describe mass produced bonsai that are sold in malls or other mass retail type locations. Often such trees are little more than young plants potted in inexpensive bonsai pots. Many times they are then rushed off to sale without having been allowed to become established, this is why they glue the rocks on, to stabilize the planting for shipping.
Some plants can grow reasonably well indoors provided the proper conditions are met. Many plants however simply will not survive long inside, unfortunately erroneous information abounds with the retailer being either unknowing or uncaring.
Without more information it would be unwise for us to advice re-potting now, but here is some information about soils so that you can begin to learn what the properties of a decent bonsai soil should be.