If you give details
eg If you said the files are at c:\program files\appfolder I can say only admins can write there. If you said I reinstalled windows. Both of the above is handled with File Permissions (type it in help). Mention programs by name. There a few older programs that check the attribute on a folder and will refuse to use if read only. Why who knows, it's window's job to guard things, programs don't have to and shouldn't do too much of it. And they got it wrong (hard to know what's worse - Read Only is 25 years old this year so they've had time to learn the rules). Plus explorer is 9 years old this year (august) so for 16 years RO meant absolutely nothing (though you could set and unset it), For 5 years you could set and unset it and only explorer cared. For the last 4 years you can't change it (by clicking anyway).
Whenever posting we here want raw data, not your theories on why it isn't working. Therefore full details, exact text of messages, full names of files and programs (and mfg if not obvious), the step one takes to make it happen, and as windows works in two modes domain and non domain that can be vital.