No option to set variable simpleads_redirect_message_show

I am using Simple ads - 7.x-1.8
I see there is a line in module - "$show_message = variable_get('simpleads_redirect_message_show', TRUE);"
But I was not able to find any option to set this variable.

How do we set this variable to false, or just change it.

Same applies for variable - "simpleads_redirect_message"

Please see if we can provide a form here to set this up.