WP edits not recognized

I wanted to display one full post plus excerpts on the front page, and was able to do so by adding:
<?php $i = 0; while (have_posts()) : the_post(); $i++; ?>
to the top of the index (instead of <?php while (have_posts()) : the_post(); ?>)
But suddenly it stopped working. So I decided to have all the front page show as excerpts, so changed
<?php the_content(); ?> to <?php the_excerpt(); ?>
That worked. But then I changed my mind and put it back to “content.” Now I still get only excerpts showing. Why won’t WP recognize my edits? I tried closing the browser and re-opening it, but nothing. All I get are excerpts on the front page.
Help! Thanks!