Question about upgrading PHP environment

Hi! So, I upgraded one of my WordPress sites to WordPress 5.1 and after the upgrade, WordPress informed me I was using an “insecure” version of PHP. I believe PHP 5.4.x was installed in my shared hosting account at Hostgator. So, I upgraded PHP from 5.4.x to 7.0. After doing so, NinjaFirewall refused to load and I was prompted to re-configure it. I tried setting up the Full WAF and NinjaFirewall can’t load. It works fine in WordPress WAF mode.

So, I have two questions:

1) What’s the best way to change the PHP environment when NinjaFirewall is already installed?

2) How can I change NinjaFirewall from WordPress WAF to Full WAF?

Thanks!