Some questions about saA

First of all I really like the app. I think it takes a little until you fully understand all the features but then it can be really helpful.
So now I just have some questions about the functions. First one is that I don’t understand how to zoom into graphs. When I’m watching my last night graph or also the other ones, I tried already a lot of times to zoom in with the common finger movement, but it just doesn’t work. Can someone explain me how to do this?

Then I wanted to know if I can select only particular tags to see how they interfere with my sleep habits. To see all of them isn’t really helpful as the screen is just too small to really get some information. Also I wanted to know if there is an option to do correlations with tags I preselected? This would be incredible revealing and informative!

Thanks for some answers and greets from Italy