I completed accounting and administrative work in my past job. Can I ensure in my CV that any future employers pick me for an accounting position?

In this case it's important to highlight the specific competencies you would like to emphasise. So if you're looking out for an accountancy role, its important to highlight your accountancy proficieny, skills and atrributes to attract the corresponding job profiles.

Just emphasis about accountancy in the begining of the CV or cover letter your current interest and objectives.