Mmk, so I got this script to work, just not the way I want it to. Basically, when you hover over an NPC, a grey SelectionBox will appear around it, and if you click on it, a red SelectionBox will appear around it. However, when you already have a red SelectionBox around an NPC and you scroll over a second NPC, the grey SelectionBox goes over it fine, however clicking on it does make the red SelectionBox appear. If you see any variables that are not used, that's because I plan to expand this script later on. Anyways, here is all the code involved with it:

Setting Player values:

game.Players.PlayerAdded:connect(function(plr)
	local character = plr.Character
	if not character or character.Parent == nil then -- what for character
		character = plr.CharacterAdded:wait()
	end
	local val = Instance.new("BoolValue",character) -- set all variables needed
	val.Name = "player"
	local val2 = Instance.new("BoolValue",character)
	val2.Name = "combat"
	local val3 = Instance.new("BoolValue",character)
	val3.Name = "talking"
	local val4 = Instance.new("BoolValue",character)
	val4.Name = "reading"
end)

mouse script:

local player = game.Players.LocalPlayer
local character = player.Character

local mouse = player:GetMouse()

if not character or character.Parent == nil then
	character = player.CharacterAdded:wait()
end

local selection = Instance.new("SelectionBox", player.PlayerGui)
selection.Color = BrickColor.new("Medium stone grey")

local cmbselection = Instance.new("SelectionBox", player.PlayerGui)
cmbselection.Color = BrickColor.new("Bright red")

local talkselection = Instance.new("SelectionBox", player.PlayerGui)
talkselection.Color = BrickColor.new("Bright green")

local bookselection = Instance.new("SelectionBox", player.PlayerGui)
bookselection.Color = BrickColor.new("Bright blue")

mouse.Move:connect(function()
	mouse.Icon = "http://www.roblox.com/asset/?id=184642130"
	local target = mouse.Target
	local combat = character.combat
	local plr = character.player
	local talking = character.talking
	local reading = character.reading
	if target and target.Parent:IsA("Model")then
		local hum = target.Parent:FindFirstChild("Humanoid")
		local p = target.Parent:FindFirstChild("player")
		local enemy = target.Parent:FindFirstChild("enemy")
		local friend = target.Parent:FindFirstChild("friend")
		local book = target.Parent:FindFirstChild("book")
		if hum and enemy and p == nil and combat.Value == false then
			selection.Adornee = target.Parent
			local targetpos = target.Parent.Torso.Position
			local distance = player:DistanceFromCharacter(targetpos)
			mouse.Icon = "http://www.roblox.com/asset/?id=165194824"
			mouse.Button1Down:connect(function()
				if distance < 40 and combat.Value == false then
					combat.Value = true
					selection.Adornee = nil
					cmbselection.Adornee = target.Parent
				end
			end)
		elseif hum and enemy and p == nil and combat.Value == true and cmbselection.Adornee ~= target.Parent then
			local targetpos = target.Parent.Torso.Position
			local distance = player:DistanceFromCharacter(targetpos)
			selection.Adornee = target.Parent
			mouse.Icon = "http://www.roblox.com/asset/?id=165194824"
			mouse.Button1Down:connect(function()
				if distance < 40 and combat.Value == true then
					selection.Adornee = nil
					cmbselection.Adornee = target.Parent
				end
			end)
		elseif p or hum == nil or enemy == nil or friend == nil or book == nil then
			mouse.Icon = "http://www.roblox.com/asset/?id=184642130"
	        selection.Adornee = nil
		elseif p~= nil and hum and enemy and cmbselection.Adornee == target.Parent then
			mouse.Icon = "http://www.roblox.com/asset/?id=165194824"
		end
	else 
		mouse.Icon = "http://www.roblox.com/asset/?id=184642130"
		selection.Adornee = nil
	end
end)

I apologize if it's sloppy or inefficient, I just can't figure out this problem right now, I'd really appreciate it if you could help.

Anonymous