I would like to have keywords to be appear Bold and variable names,Comments and Strings should be in normal style. is that possible
You can create your own custom Syntax Highlighting rules in EditPlus using .stx files. There is information about how to do this in the EditPlus help file - search for syntax highlighting.
But you'd need to find a way of denoting what is a variable and what is a keyword... this maybe possible if you code with consistency, e.g. use CamelCase for variable names and use for comments.
You might find another EditPlus user has already created a syntax file that meets your requirements. Check out the repository of EditPlus syntax files.