Sites hacking occurs oftenly

Hello All,

I had some sites on one hosting panel.but it had hacked regularly.I thought issue is of hosting server so I changed hosting provider.

I cleaned all sites and started moving on new server.But one of those is hacked again.

Ability to make comment disabled and scanned with wordfence plugin.But still some malicious code found in my site.

Please let me know the reason and what more steps should I follow to avoid this hacking.

Thanks