While doing the parallel line method by using the cadtools its asking the distance in meters but i need the parallel in feet values(I need to enter the distance in feet values). currently we are using the project file with the coordinate system as WGS84 EPSG:4326. I have changed the layer projection for feet values but its not working properly. can you please suggest on this that how can i change the units from meters to feet without changing the projection of project file.
I haven't used the cadtools plugin, but your problem sounds identical to a limitation in the "Improved Polygon Capturing" plugin, that we use to enter lines in with a known length (in feet).
Unfortunately, I have not found a way without changing the project file projection. But here's what we do: Our core data is in database layers, with EPSG:4326. We have "entry layers" in a feet-based projection (I made my own, but the reasons for that are complicated - just find an existing CRS in feet that covers the area you're working in). The QGIS file is set to the feet-based projection, and coordinate transformation is set to 'on'.
With this setup, we can draw lines on our "EntryLines" layer using known length. Then we transfer the results to our lat/lon tables. (We use a plugin that does the transforms in the database while it does lots of other stuff at the same time; but before that, we had great success with copy & paste within QGIS - copying from a layer in one CRS and pasting to one in a different CRS seems to do the transform for you!).