To help us help you, get to a terminal window on your system and type the following commands, then paste the results into your question:
Please post what the following return:
whoami
cat /etc/os-release
uname -a
grep dtparam /boot/config.txt
groups
ls ~/Dexter
more ~/Dexter/Version (file may not be found)
more /opt/Sam_Dev/webapp/version.txt (file may not be found)