Visual Math 4D

I used this app's export function for papers and lectures several years ago. I recently came back to it, to plot some practice error surfaces for adaptive filters. But now I can't find the "Save" button/menu to save the whole set of equations, not just the exporting plots. The export menu doesn't seem to have a Save item. I checked with the dev's website but couldn't find anything. Any help appreciated.

This is a useful tool to have, but on my ipad pro(9.7-inch)(ios 13.5.1) I seem to be unable to hide the calculator as it is done in the video, and it would be nice to be able to use the whole screen for the visualization. I have tried opening the menu, but the calculator doesn’t react(on my iphone opening the menu closes the calculator), and the calculator button doesn’t do anything. I have tried reinstalling the app and restarting the device, but it didn’t help. Is this a bug, is the calculator simply a permanent fixture, or am I just stupid?

I frequently use Visual Math 4d. A friend sent it to me because I always talk about math and draw functions or explain the algebra behind things... I use the App to combat boredom, to learn about new domains, and, the elegance of the Visuals allows me to enjoy even the simplest parameters. I would recommend this app to anyone. I wish there was a community that discusses this app, as I have not seen any documentation or tutorial videos or message boards. The app seems to be powerful enough and maybe I am not looking in the right places. Thanks for the great app!!