If your version is older than 9.0, then no chance to open project created by windows version on Mac, as the project files (.wve & .wsve) and software are not interchangeable between the two operating systems because of the software architecture. As alternative, you can export the project to a video file first, such as .mp4 from windows version first. Then import the video to the project created by Filmora for Mac as input.
And for project made with 9.0, you can archive the project first then open in different operating systems.
It is not suggested to open project made with the old version to new version9, as they share the different software architecture and built-in effects. So you are suggested to finish the project in older version and export it first. Then create new project with version9.
Yes, you can adjust the aspect ratio if you are using Filmora9. You just need to select "project settings" under "file" to adjust it directly.
Yes, upgrading to Filmora9 is free. You can use the same Wondershare ID account to activate Filmora9.
To use the Green Screen, please follow below steps:
1. Firstly press the Import button to load the regular background clip and the green screen clip to Media Library.
2. Drag and drop the regular background clip and the green screen video from the Media Library into the Video track and the PIP track of the timeline respectively.
3. Right click the green screen video, then select Green Screen, in the pop-up window, go to Green Screen tab, tick the option of Green Screen (Chroma Key). And then adjust the intensity accordingly to match with your original clip. Press OK to save the settings.
4. Lastly go back to the preview window again, adjust the size and the position of the green screen video by dragging the small circles around the video.