Does not work

I cannot make this plug-in working. Test emails are fine, but when the user registers it sends old email. Is there a way to disable the default email sender.

I have read here on the forum that there are could be conflicts but I how do I figure what is the plug-in that needs to be fixed.I have mostly woocommerce plug-ins. Do not see how any of them would use emails.

Please, advise.

https://www.ads-software.com/extend/plugins/welcome-email-editor/