Install Footer Script

I’m trying to install a footer script that needs updai=ting in my wordpress site with genesis theme and wordfence is up to date.

I have made sure that my IP address is whitelisted in wordfence advanced firewall options. When that didn’t work-
I have tried deactivating wordfence. When that didn’t work –
I removed the enhanced protection files thru the wordfence interface.

I still cannot change the footer script and I keep getting this message on my sites customize.php url –

Looks like something’s gone wrong. Wait a couple seconds, and then try again.

What do I do to edit these scripts and get my site to accept them?

Thanks.