how ti change read post/ next post/ previous post button

You can use this function.

function read_post_button_text($text) {
    return 'New Text';
}
add_filter( 'frontier_continue_reading_text', 'read_post_button_text' );

Or this http://ronangelo.com/change-or-translate-text-on-a-wordpress-theme/

http://wordpress.org/support/topic/revert-back-to-old-post-navigation?replies=4#post-5020940

I don’t understand what you’re saying. There is only one button for each post on the posts page aka blog page.

The code I added above changes the text that says “Read Post” on the excerpts button.

The second url I posted shows how to change the Next/Previous Post in single posts into Next/Previous Post Titles.

I understand from your last reply that I can’t change the read post button to the title of the post.

You mean the “Read Post” text should be replaced with the post’s title? Yes, you can do that but then you would have two titles on a single article. I don’t see the point in that but here’s what you would add to accomplish that:

function read_post_button_text($text) {
    return the_title();
}
add_filter( 'frontier_continue_reading_text', 'read_post_button_text' );