To save any records, including from the 1921 Census of England and Wales, you can add them to your family tree or download the image. You can add a record to your tree from both the transcript and the image. By adding a record to your family tree, you can receive hints for that person, this will help you find them in other records.
On the image viewer there are Options and Viewer controls. Within the options section, there is an add to tree button and a download button.
On a transcript page there is an add to tree button. Alternatively, if you want to transfer the contents of the transcript elsewhere, use the ‘Copy to clipboard’ button and paste anywhere on your device. Either the household members table or an individual's record transcript can be copied.
If you want to go back to a record you have purchased but not saved, you can find all the records you have viewed by visiting ‘My Records’. When logged in, this will be in the menu at the top of your screen.
You can also redo the search for your record, all previously viewed records will have a tick in the transcript or image buttons within search results.