Some Fusion training videos might be a better place to start. There are some excellent tutorials on YouTube – people like JayAreTV, Casey Faris etc are good starting places. It is sometimes easier to get your stills into the edit timeline, get the duration set and then open that in the Fusion page from Edit.
The one tip i will give you about the paint tool, is that it defaults to multistroke mode, which only does your paint work on the frame you are working on, unless you specifically tell it to paint on a set number of frames.
If you want to paint on the entire length of a still section, you need to change you mode to “Stroke” before you do any painting. Stroke will add the paint strokes to your entire timeline length. Hover over the paintbrush icons at the top of the interface, and you should find stroke and multistroke.
Thank you for your replies, What I did not mention was the fact that the same thing happens If I am using the rectangle or polygon I get just the single end frame. One thing I have noticed is this: If I had a still of a cup and I add a keyframed fast noise to add a steam effect, the effect is then over the full still clip. regarding ‘paint’ it is not the actual build-up of frames, it is just the end result. In other words, If I wanted to remove a tree from a wood and replace it with say a shrub nearby. it is just the end result I was looking for.
I just thought people like to know the answer to my question: In the fusion page and using the “paint” mode If you want to cover the full clip instead of just 1/24th of a frame, you must use the “stroke” and not the multi-stroke mode. Why I do know but it works.