Problems working with Nicerpage

I am playing with a “sandbox” site so I can get up to speed with the app - purchased license for ver. 3.3 a while ago - when working with the header - I have a background image with a logo and a menu on top of the image - when tweaking the elements on each device layout, when I come back to a device, items will have moved - after about 6 attempts at this, I finally got things to stay put.

Also, I have some text on some of the devices that is not showing up on other devices.

I have a gap between the footer and the body content I cannot close.

As I am working - the page will suddenly just go completely blank.

My content has disappeared from from the tablet portrait device (except for the header) - I did not do this.

There are other issues , but these are the main things.

Maybe this is all user error - please advise. I was considering purchasing the upgrade to ver. 4 hoping that stability and ease of use issues would be addressed - I am glad to pay for the upgrade for a program that works. Please reply ASAP - thank you.