For anyone who experiences a similar problem to mine and comes across this post, unfortunately, I could not find a way to format my existing document by setting styles only. Using styles only worked fine before starting a new document but as mine already existed and was hundreds of pages long, this did not work for me, I didn't do it by any 'proper' way but got the job done via other methods, i.e. I created the styles for the four lines of text as partly described in this thread, however, instead of setting bullets, I used Find and Replace to add normal letters to use as my bullets and selected the relevant style for each line (within Find and Replace). To get the right space between my 'bullets' and text and have them all line up correctly, I reduced the default tab stop for the whole document and used a hanging indent. Hope this helps anyone looking for an answer to my original question:

Thanks.