I would advise three things:
First, given that you experience the thoughts as bad, it is possible that you are ignoring the emotions surrounding the thoughts. If you are upset by the thoughts that arise, it is also important to acknowledge that as "disliking" or "upset", etc.
According to the satipaṭṭhāna suttaṃ, Buddha had stated that any consciousness, thought or impression associated with lust must be recognized and mentally noted as such. One must recognize and be aware of Citta (consciousness, thought or impression) which is associated with or dissociated from (a) lust or craving: (b) anger or hatred; and (c) ignorance or delusion.
-- Mahasi Sayadaw, Vipassana
Second, the practice of insight meditation isn't to make thoughts or memories go away; what you are experiencing is the characteristic of non-self - that you can't control your mind, no matter how you try. Insight meditation helps you to see this, so you are less affected by the experiences.
Next, the yogī will become convinced that all these psycho-physical phenomena are occurring of their own accord, following nobody's will and subject to nobody's control. They constitute no individual or ego-entity. This realization is anattānupassanā-ñāṇa.
-- Mahasi Sayadaw, Practical Vipassana Meditation Excercises
Third, meditation is a gradual training; just like any training, it takes time to become proficient. As the Mahasi Sayadaw says:
As the yogī goes on noting thus, he will be able to note more and more of these happenings. In the beginning, as his mind wanders here and there, the yogī may miss noting many things. But he should not be disheartened. Every beginner in meditation encounters the same difficulty, but as he becomes more practised, he becomes aware of every act of mind wandering till eventually the mind does not wander any more.