To work with architectural units (inches and feets), it is necessary to set architectural units in several places:
1 - in Units dialog - Length type and Insertion scale,
2 - in Dimstyle dialog for current dimension style on Primary units, Alternate units tabs,
3 - in Scalelistedit dialog: click Reset button, then choose Imperial scales,
4 - in Design settings dialog: Main options tab - Design - List of drawing scales - Document only or All.
To apply all this settings for all new documents, save empty drawing with these settings as dwt file and use this file as default template in Options - Template usage - For new documents - Default template file name.