Securely setting a global variable

[Kanegasi]

I have the following code:

function PLAYER_LOGIN()
 
    BUFFS_PER_ROW=12
    BUFF_MAX_DISPLAY=36
    BUFF_HORIZ_SPACING=-1.25
 
end

This works great, however I get the following silly error when I try to rightclick buffs in combat:

Message: Note: AddOn attempted to call a protected function (CancelUnitBuff()) during combat lockdown.
Debug:
   [C]: CancelUnitBuff()
   ..\FrameXML\BuffFrame.lua:280: BuffButton_OnClick()
   [string "*:OnClick"]:1:
      [string "*:OnClick"]:1

I'm not altering these in combat. The values do not change beyond login. Is there a secure way to change these three variables?

I am not interested in any buff addons. I just want to change these three global variables once each session.