[Xrystal]

Only by editing the nUI_HUDSkin_#######_Castbar.lua file of the respective hud layouts available in nUI/Layouts/Default/HUDLayouts.

This is what it is set to by Default:

		["Casting"] =
		{
			anchor =
			{
				anchor_pt   = "BOTTOM",
				relative_to = nUI_HUDLAYOUT_PLAYERTARGET.."Bottom",
				relative_pt = "TOP",
				xOfs        = 0,
				yOfs        = 130,
			},		
			options =
			{
				enabled = true,
				height  = 40,
				width   = 375,
				inset   = 0,
				strata  = nil,
				level   = 4,
				
				orient       = "LEFT",
				persist      = false,
				show_bar     = true,
				show_gcd     = false,
				show_latency = true,	
				overlay     = "Interface\\AddOns\\nUI\\Layouts\\Default\\Art\\nUI_BarOverlay1",
				
				cur_time =
				{
					enabled     = true,
					fonsize     = 11,
					justifyH    = "RIGHT",
					justifyV    = "MIDDLE",
					anchor_pt   = "RIGHT",
					xOfs        = -5,
					yOfs        = 1,
					
					color = { r = 1, g = 1, b = 1, a = 1 },
				},
				
				spell_name =
				{
					enabled     = true,
					fonsize     = 11,
					justifyH    = "LEFT",
					justifyV    = "MIDDLE",
					anchor_pt   = "LEFT",
					xOfs        = 5,
					yOfs        = 1,
					
					color = { r = 1, g = 1, b = 1, a = 1 },
				},
				
				msg_label =
				{
					enabled   = true,
					fonsize     = 13,
					justifyH  = "CENTER",
					justifyV  = "MIDDLE",
					anchor_pt = "CENTER",
					xOfs      = 0,
					yOfs      = 1,
					
					color = { r = 1, g = 0, b = 0, a = 1 },
				},
			
				border =
				{
					backdrop =
					{
						bgFile   = "Interface\\Tooltips\\UI-Tooltip-Background", 
						edgeFile = nil, 
						tile     = true, 
						tileSize = 1, 
						edgeSize = 5, 
						insets   = { left = 0, right = 0, top = 0, bottom = 0 },
					},					
					color =
					{
						border   = { r = 0, g = 0, b = 0, a = 0 },
						backdrop = { r = 0, g = 0, b = 0, a = 0.75 },
					},
				},
			},
		},