Since WordPress Version 5 and the new Gutenberg editor are due to be rolled out late November 2018 I'm getting a lot of questions related to preventing automatic updates to WordPress sites.
First install Easy Update Manager. The easiest way to configure this is to change the following settings on the General Tab:
Secondly, install Disable Gutenberg, the default settings are OK.
Once both of these plugins are activated and configured your site will not automatically update to Version 5 and Gutenberg. I strongly suggest putting a copy of your site onto a staging site and testing any major upgrades before rolling out the upgrade onto your live site. This is particularly important for eCommerce sites and membership sites where payment processing and checkouts are highly complex.
As always I'm here at RosieBrent.com to support you every step of the way. Get in touch or raise a ticket to order your upgrade support project today.