An easy fix is to shampoo more often. But, you will need a correct shampoo. There are many categories of dandruff shampoos sold over the counter. Start with one from Neutrogena ...the Tgel shampoo works well but I would only recommend it for brunettes, since the tar can discolir lighter hair. Their Tsal shampoo would be safer for the latter. Head and Shoulders also makes a variety of shampoos to target dandruff. If not successful, see a board certified dermatologist for prescription strength shampoos and topical medication. Sometimes there are thick areas of dandruff that need to be treated with topical foams or liquids.

First and foremost, I would recommend an evaluation by a dermatologist to confirm that what you have is dandruff. If so, there are prescription topical medications and shampoo that you could use. Over-the-counter Head and Shoulders is another option.
Hope this helps!

Medicated shampoo lather and rinse in 5 minutes. Daily if necessary

OTC treatments include T-gel shampoo which is tar based and head n shoulders a salicylic acid shampoo. Both are helpful with mild dandruff but more aggressive treatment may be needed if it is difficult to control. See a board-certified derm if the shampoos are not effective.

Various anti-dandruff shampoos like Ketoconazole, zinc pyrithione (head and shoulders) or selenium sulfide (Selsun Blue) can be helpful. When that is not sufficient, your doctor can prescribe topical corticosteroids

Topical steroids, creams and solutions, and anti-fungal and anti-inflammatory shampoos would help. Visit your local dermatologist and discuss your options and diagnosis.