The simple way to decide if you should start a new topic instead of replying to an existing topic is to look at the title of the topic. Does what you want to say relate directly to that title? If so, it’s fine to reply. If not, please start a new topic. If you ever find yourself typing the words, “I know this is off-topic, but…,” that’s an indication that you need to start a new topic.
For those who interact with the forum primarily via email, please don’t reply randomly to the first post (or summary) you find in your inbox. You’ll confuse readers (and likely won’t get a useful reply) if you ask an off-topic question in a topic about something entirely different.
One final piece of advice. If you want to communicate directly with someone who has posted in the forum, but you don’t want your message to be public for everyone else to read, click their name in a post, and in the bio that appears, click the blue Message button.
That creates a new message that looks similar to a forum reply but is addressed directly to the user in question. It even fills in the title appropriately and includes a link to the referenced post.
Feel free to message me this way if you need to get in touch privately!