Algae needs light, any type of light. In a planted tank, an increase in algae generally means something is wrong with the balance and the light has become greater than what the plants can use. There has to be a balance; plants will photosynthesize full out as long as all nutrients are available and they have sufficient light (intensity). As soon as something essential is no longer available, plant photosynthesis slows and may even cease. Botanists term this the law of minimum. Light should always be the limiting factor. Algae can use any light and once the plants stop photosynthesizing and light continues to be present, algae takes advantage.
This is why the temptation we all share to limit nutrients at the first sign of algae is actually the worst thing we can do. We should increase the nutrients to balance the light--or reduce the light duration/intensity. Of course, if the missing nutrient is CO2--and it usually will be--increasing other nutrients will in this situation only make things worse. Reducing the light, whether intensity or duration, is always to best method to control algae. And duration is usually what should be reduced, provided the light intensity is sufficient and not beyond the needs of the plants.
With this in mind, it should be no surprise that algae usually first appears on floating plants. They are closest to the light so it is more intense. In this case, reducing nutrients in the water will only make it worse, since the floating plants are fast growing and with all that light, they need even more nutrients. They can obtain CO2 from the air, so here it is the easy-to-add nutrients, via a liquid fertilizer, that should be increased.
The above is general; there are various types of algae and many aspects of the natural system that can all play into this. Many others have written about nutrients causing this or that algae--iron, phosphorus, CO2 and others. But generally it is wisest to start by reducing the light to prevent algae from increasing.
To specifics. The second algae in the photos is brush, and it is increasing on dead or dying leaves. I would remove that whole stem of leaves, they are all dying anyway, as shown by their yellowing throughout. Even the roots on that stem are not alive--they would be white like the others if they were. I am most plagued by brush algae, and I have noticed that when it increases like it is here in these photos on a leaf--and it will do this on one leaf only of a sword plant--that leaf is dying; when I remove it, the stem at the base has turned brown showing that nutrients are no longer traveling to and from that leaf. I don't know if the leaf starts dying (as leaves do now and then) and the algae latches on, or if the algae starts the dying process. But there is a connection one way or the other.
Something that must be remembered: it is not natural tonot have some algae. Algae is an essential part of all life on this planet [except for the life forms living in the ocean volcanic vents which are very different]. An aquarium that has no algae is not natural. But we have to keep it in check.