Treatment includes several options, the doctor will prescribe for you the best one after evaluating your spots. Several spots may look the same to you but may have a different diagnosis according to a dermatologist.
Different diagnosis means different treatments depending on the diagnosis of the spots.
Lentigo is treated by several options, retinoid creams, hydroxy acid, vitamin C, cryotherapy, laser treatment, bleaching creams, etc. These options are to be considered after a doctor's prescription depending on your skin type too.
As for tenea versicolor, it is a fungal infection of the skin increased in summer and high humidity, they may be brown with different shapes, they come and go and are recurrent. They are removed by the application of topical antifungal creams.
Check with the doctor to apply sunscreen to protect your skin.