Currently, the gem will not automatically generate the view for you to edit. I think it's one of the things that people have asked for. In the meantime, you can manually create the file. If you look in the gem's:
devise_security_extension/app/views/devise/password_expired/show.html.erb
You'll see the current template for the view that the gem uses. Copy and paste this file into your views/devise/password_expired/show.html.erb
You'll then be able to edit it the way you'd like.
The file looks like this:
<h2>Renew your password</h2>
<%= form_for(resource, :as => resource_name, :url => [resource_name, :password_expired], :html => { :method => :put }) do |f| %>
<%= devise_error_messages! %>
<p><%= f.label :current_password, "Current password" %><br />
<%= f.password_field :current_password %></p>
<p><%= f.label :password, "New password" %><br />
<%= f.password_field :password %></p>
<p><%= f.label :password_confirmation, "Confirm new password" %><br />
<%= f.password_field :password_confirmation %></p>
<p><%= f.submit "Change my password" %></p>
<% end %>