As far as what I've found those icons in the Notification Area/System Tray can't be changed, established when a program is installed and assigned to that area. The icons on the Taskbar for programs can be changed but it would require unpinning programs, creating new shortcuts on the Desktop, using Properties of them to Change icon and pick something desired. If a program doesn't include more than one icon then a .dll file in Windows will have different icons or a person could use Paint/MSPaint to create new ones and store them in a .dll file then point the Properties to that file and the icons in it. A caveat, one must be careful in customization of Windows that they don't run afoul of the EULA.