Homegroup sharing Win.7, to Win. 10

Hello all,
I am trying to share my files, mainly documents and pictures between my (3) laptops. On my 2 laptops running
Windows 7 this is not a problem, but I am unable to share between Win. 7 and Win. 10. I can startup the homegroup, it will
recognize the other device on the network (private connection via ethernet cable) and I can move files from the Windows 10
computer to the Windows 7 machine, but not vice versa. If I try to drag and drop into the folder for the other machine, it tells
me I need permission.
I have checked and rechecked the appropriate fields needed for sharing, but it won't work to send from Win 7 to 10.
I uninstalled my Norton Security on the chance that it was preventing me, but no go.
My Windows 10 is Pro. version, Windows 7 is Ultimate.
I only use the Windows 10 as a backup computer and I can transfer files from Windows 7 by dragging them to a thumb drive and inserting that in the Win. 10 machine. But there must be a better way?
Just another reason why I don't like Win. 10. Has any one else experienced this?
Thank you for looking.

Welcome to the forum. What folders are you trying to access if it's in the users profile you won't have NTFS rights even on the PC logged in as another user you can't get access. You can create a folder and use that or you can use Google drive with that you save files to local folder and it will sync onto other PC on its own you get 15 gig free and your files are all backed up safe

Thank you for the reply, why will it work on Windows 7? Without doing what you suggest?