LibreCAD provides settings for both drawing units and display units.
Open LibreCAD and go to Edit - Drawing Settings - Drawing Options - General tab - Drawing Units make sure you select "Inches" as the unit of measure.
Then go to the Display tab in the Drawing Options dialog - Display Units section make sure you also select Inches as the unit - OK to save the changes.
After making these changes, the picture should be displayed in inches, according to your settings.
instruction page
Drawing Preferences