Check this post out to answer your question about MS: What is MS how to change?
If you don’t have any keyboard or mouse software to change this you could try this:
your best bet then would be to download and install auto hot key from here: https://www.autohotkey.com
Once installed right click anywhere on your desktop and click new then Autohotkey Script. Once its open delete everything inside and put this code in:
#IfWinActive World of Warcraft
$3::
GetKeyState, state, 3, P
if state = D
Loop
{
Send {3}
Sleep, 70
return
}
#IfWinActive
Change all the 3’s to what ever key you have your macro on. the line with sleep is your MS so in this case 70. Save it to something you will remember. Right click that file and click run - go into game and hold key it should now work.