Put comment subscribe checkbox above submit button

While the plugin doesn’t offer an option allowing you to change the placement of the subscription options, you should be able to add a custom submit button thanks to the comment_form action:
https://codex.wordpress.org/Plugin_API/Action_Reference/comment_form

You can use the hook to add your own submit button, and define a custom priority so the button is hooked very late. If it’s hooked later than the default priority, 10, it will be added after the subscription options, that are themselves hooked at the default priority, 10.

All this requires customizing the function used to output the comment form in your theme, though, so it can only be done if you’re comfortable editing PHP files to customize your theme.

I hope this helps.