The brown spots may be some type of disease but it is difficult to say without seeing them. Your best bet is to take some leaves showing the damage to your County Extension Office and see if they can identify the cause of the damage. They would then be able to recommend an appropriate remedy for you to use. The light green leaved one in the sun may be struggling with too much sun but I suspect it just needs some fertilizer and supplemental iron. Choose an azalea/camellia food and that should provide all the nutrients it needs. Loosen the surface of the soil around it gently about 2 inches deep with a spading fork. Just break it open a bit, don't turn it over. Spread the fertilizer and top it off with an inch or so of peat moss and a couple of inches of pine needles or pine bark mulch. Then water it in well.
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