Hello and welcome to the forum.
First off you need to understand that you may have conflicting share permissions based on group membership.
The Everyone identity All interactive, network, dial-up, and authenticated users are members of the Everyone group. This special identity group gives wide access to a system resource.
SOURCE: Understand Implicit Groups and Identities in Windows Server 2008
So basically "everyone" (users, authenticated users, guests, etc.,)
Second.... file sharing can sometimes be a bit complicated without involving the "Simple File Sharing Wizard" so my recommendation is... turn it off
Win Logo Key + E->View Tab-> Options Icon Drop Down->Change Folder and Search Options->View Tab->Scroll to Bottom-> Untick "Use Sharing Wizard (Recommended).
Now, in the interest of maintaining some sanity, make sure all network nodes are members of the same Work Group.
Win Logo Key + E -> Right Click Computer and choose properties. You can use the "Change settings" link to alter the Workgroup name on each node if needed.
Now when sharing a folder.
Under the "Sharing" tab, use the "Advance Sharing" button. Check "Share this folder" and click the "Permissions" button.
The only thing you need in there is the "Everyone" group... "Full Control"
Now you lock down you actual permissions using the "Security" tab, which controls NTFS permissions (on NTFS volumes)
This is where the issues with understanding Group Membership, Nested Groups, and Nested Users inside of those groups.....AND the fact that when share permissions and NTFS permissions are combined (and they are) the most restrictive permission wins.
So if you have a user named John Smith
And you grant John Smith Full Control of a particular shared resource
But then you in turn grant the "Users Group" read only access to the same shared resource, then John Smith will only have "Read Only" access to the shared resource.
If you have the time you can spend it reading this TechExams.Net - MCSA/MCSE 70-290 TechNotes: Shared Folder and NTFS Permissions
AND of course if it is a Fat32 volume rather than an NTFS volume you can ignore most of the above except the part about conflicting permissions based on group memberships.