You can help your advert to appear higher up the list, at no extra cost, by mentioning the job title 4 times in the advert itself, even if it feels clunky, this is what Google and Indeed and other search engines use to rank posts, they are looking for commonly used words so the more often you use the words the higher up the list your advert will appear, also if there is another commonly used job title for the same role you should mention that title in the advert text as well so that when people search for it the advert will also be drawn into the search.
Below is a snap shot of an advert showing how to incorporate the job title 4 times in the advert:
More details about job titles can be found in the section headed, Job Titles and Alternative Job Titles.