updating from PC to DF and back

I have a 385 HB combo with a Navionics basic map card. I have always been able to call up map charts from Navionics and update data on them such as creating and naming a waypoint or renaming ones I had previously loaded via an SD chip from the DF to the PC map.

I recently purchased an Elite7 DSI combo unit and a Navionics premium card. I was able to go on the Navionics site and download the latest update to the map card, but I cannot find and app that will let me update the map on the PC and copy to an SD chip to download to the Elite 7. I thought I could put a blank SD chip in my Elite unit and load any changes to it and then transfer to a map on the PC but I don't see any way to do that.
When I went to the "Web App" on Navionics it let me open the lake charts but it won't let me write to them.
On my HB I could transfer this data back and forth. I also got a message that my chart plotter was an old version and I need to download the new version but I can't find any such option on their website.

I know you can't alter the Map card other than via the updates from Navionics but I could transfer data back and forth using a clean SD chip.
Is this feature not available on the Lowrance units? If any one is doing this I would appreciate a tutorial on how to do it.

Thanks

SeaRay