Ron Howard refuses to watch his hit movies. The ‘Happy Days’ actor-turned-director, 70, has spent years making some of Hollywood’s biggest blockbusters including ‘Splash’, ‘Cocoon’, ‘Backdraft’ and ‘Apollo 13’, but said he doesn’t like to dwell on his achievements. He told People: “Frankly, I don’t go back and watch my movies, so it’s been a long time since I’ve seen ‘Splash’.” But Ron said about the beloved 1984 comedy, which starred Daryl Hannah as a mermaid discovered by Tom Hanks: “Making the movie was so much fun. “We just laughed every day. It was such a buoyant, romantic, funny combinat…