Create persistent lines across all symbols

Good afternoon Gentleman,
I’m absolutely new to Amibroker. I want to add a couple of horizontal lines onto the Williams%R. These are to be a certain levels such as -45, -65, -20, -80. I want these horizontal lines to stay where they are regardless of what symbol I go to. Is there an easy way I can do this? Thanks in advance for your help.


PlotGrid( -45 );