These are some phrases that you can use when you want to change the subject in a conversation.

Conversation Gambits: Changing the Subject

We can use this to change the topic, or to show that you have finished.
"So I spent hours helping him. I blah blah.....blah. Anyway, I won't ever do that again."

We use this when we find an excuse to move on to something else.
A: I had a lot of fun playing PUBG last night.
B: That reminds me, have I invited you to our chess club yet?

We use something to move on to another topic.
A:I had to work overtime again last night. I couldn't believe it. Third time this week!
B: Speaking of work, did I tell you Eddy has found a new job? He loves it.