What you're asking for (with the second sentence there) is an entire course on bonsai. Maybe you don't realize it's a huge subject, and all you'll get is tiny tips on individual situations here, but if you'll say which trees you have, be specific about where they are in your environment, under what conditions, how much and how often you water, what soil mix they're planted in, etc., maybe someone can help. Every tree in the universe is different and everyone has a different environment at home, so...