Without knowing more its hard to say. There may be some liability if you knew about any dangerous conditions and tolerated them. This is a fact issue and every one is different. This why we have insurance to protect against these issues.
You could possibly be responsible if the pool fence does not meet local code. You could also be responsible if you were aware of a dangerous condition (or should have been aware...) that causes an injury. You should consult your local building code to see what kind of ordinances apply to above-ground pools, if any.
This answer is not intended to be used as actual and specific legal advice, and this answer is not intended to create an attorney-client relationship. I am happy to provide basic answers and to speak in terms of generalities, but I am not intending to give specific advice that could be construed as forming an attorney client relationship. I offer free consultations, and I am always happy to speak to potential clients personally about their legal questions. Thank you and good luck!