Earthbound spirits are simply other dimensional beings. Since space and time is an illusion and doesn’t really exist you exist within an infinite amount of vibrational levels simultaneously in the now. Sometimes “bleed-throughs” can occur which are elements of other vibrational levels that are perceivable by human senses. This usually occurs to those that accept this kind of occurrence as being part of their reality, accepting the paranormal as simply normal.

Other dimensional beings cannot infringe upon another’s freewill without permission from that specific individual, this is why ouija boards and enchantments work so well in making a public declaration of permission for other beings to communicate with the recipient. There is nothing to fear in these instances as the different energy signatures can be hard to get used to at first. The veil also prevents the occurrence of other dimensional beings being perceivable to the human senses.

This is what occurs in relation to spirits that you say are Earthbound.