When he is told that by many Americans, white, middle to upper class, he is considered a mischief-maker firing random shots at anything that pokes above the horizon, Ambassador Andrew Young says he is unaware of such a feeling. That was in the wake of the uproar over his remarks downgrading the presence of Cuban troops in Africa. Those remarks seemed to go contrary to what President carter himself had said on the subject.

If I should be an embarrassment to him, Young says in his serious, soft-spoken way, then I would leave this job. I would find another way to work for him.

He believes the role of the Cubans has been greatly overplayed in the press. Both Soviet and Cuban forces could be mired down in Africa as the United States was sunk in Vietnam.

Scare themes get far too much prominence. Six months or a year ago no one had heard of the Horn of Africa; today it is treated as an immediate menace to American security.

Young adds up the pluses for the United States in Africa, Somalia, which was at war with Ethiopia over the Ogaden - a thousand miles of sand. In Young's words - has a close relationship with the United States and is the recipient of aid in various forms. A new American ambassodor is soon to go Ethiopia to renew relations there.

In Angola, Gulf Oil does something close to a $100 million business in oil. That is the chief source of money for operating the government and obtaining essential imports from abroad. If the Cubans are there in any number, it may be as order keepers. Young notes that 300,000 to 400,000 white Portuguese left their former colony with scarcely a casualty, and that some whites remain. From Guinea, once considered a Soviet fiefdom, Sekou Toure has several times sent an invitation to Young to pay a visit.

On the massacre at Kolwezi in Zaire, he has some interesting ideas. He believes the rebel invaders came in not to slaughter Whites but to disrupt copper production and throw such a scare into European technicians that they would not come back. Since copper is the heart of Zaire's economy, the country, once the Belgian Congo, would be brought down.

He notes, not without bitterness, that while the slaughter of the whites has received prominence, little or nothing has been said about the killing of black civilians. Several hundred blacks may have been shot at the same time that their dwellings were destroyed during the raid.

But Young's conviction - his optimism - comes out strongest on the issue that looms largest. That is the future of Rhodesia and subsequently of South Africa. He believes that if the guerrillas can be persuaded in take part in a black majority Rhodesia government there can be a transition without civil war and bloodshed. That peaceful transition can be furthered by stationing a U.N. peacekeeping force in Rhodesia for a transition period and also in Nambibia (South-West Africa).

If that can occur in Rhodesia, then ultimately a similar transformation can take place in South Africa. While this may sound wildly optimistic, it represents Young's deep and continuing involvement with the racial crisis in southern Africa. He has never hesitated to speak out, although he has kept the confidence of all parties to the conflict.

As American ambassador to the United Nations, Young has in my memory, been far more active than anyone in that role. He has been continuously concerned with the brambles of the African thisket. He has called practically everybody racist, including the Swedes, to their considerable surprise, and the residents of Queens.

But how to grade this dedicated activist? Plus or minus? I have asked this question of several Western diplomats here at the United Nations, and they come down on the plus side. As one who did not wish to be identified by name put it:

"You owe Ambassador Young a considerable debt. More than most Americans understand, he just developed a link with the Third World countries. Young has assured them of America's intentions as perhaps no one out of the conventional white establishment could have done. That is distinct gain and one that, all things considered, is likely to stand you in good stead in the future."

That is what I heard from others. At times he is irritating. But his intensive efforts to avert bloody civil war and bring about a peaceful solution were given a B-plus if not an A on his report card.

I think of the frustration his predecessors - notably Adlai Stevenson - suffered in a role that has more often than not been show rather than substance. I feel that frustration will never trouble Young. And I feel, too, that out of his dedication to Carter he would not hesitate to resign if he considered himself an embarrassment to the president.