Change has never been welcome in this little South China peninsula, the oldest Western settlement in Asia, and so the last few years have been uncomfortable for its Portuguese and Chinese residents.

The 1974 leftist revolution in Portugal created a real fear that Lisbon would jettison this community of textile mills and gambling casinos just as it did its vast African colonies. The worldwide recession cut into the tourist trade; then China began one of its great periodic political upheavals, which always fill Macao folk with dread.

But a young Portuguese army colonel installed as territorial governor late in 1974 seems to have calmed the residents and the important bankers in nearby Hong Kong and let the sleepy 16-square-mile pursuit of trade and relaxation.

The ferries and hydrofoils from Hong Kong are gorged with gamblers and tourists, arriving each month in numbers nearly equal to the territory's 300,000 population.

Last week Col. Jose Eduardo Garcia, Leandro signed a contract with private interests for a huge resort on one of the territory's offshore islands. Saturday he is scheduled to sign an agreement for a harness-racing stadium on the other offshore island.

China's semiofficial representatives in Macao are involved in both deals. The new leadership in Peking quietly accepts the status quo in both Macao and Hong Kong as a vital source of foreign exchange.

"When I came here Macao's political situation was more ambiguous than it is now," said Leandro in an interview. "Political developments in Portugal affected Macao because the worst period coincided with the peak of the international recession," he said. He added that after the new Portuguese constitution defined Macao's status and the world economy began to recover, so did trade and tourism.

American tourists in particular have become infatuated by Macao's charms. About 29,000 visited in 1975, but that number jumped to more than 41,000 last year. Americans flocked not only to the Jai Alai court, dog track and casinos, but also to quieter corners of the settlement, where there are several Old World restaurants.

Leandro vehemently denies persistent rumors that Portugal has tried to give Macao back to China.

"I think such statements are worked up by professional speculators," he said. Sources close to Ho Yin, Peking's millionaire representative in the settlement, also deny the by Portugal's Soviet-linked Communist Party to embarrass Peking.

Leandro denies that the Portuguese Communists have any important influence on Lisbon's foreign policy. The Chinese have shied away from establishing diplomatic relations with Lisbon despite Prime Minister Mario Soares' active wooing of Peking.

Chinese suspicion of the forces behind the shifting political climate in Portugal does not extend to Leandro, who seems to enjoy the respect and friendship of the leaders of the Chinese community. Ho Yin recently escorted Leandro's parents and mother-in-law on a tour of southern China.

The 1974 Portuguese revolution did bring a redefinition of Macao as a Chinese territory under Portuguse administration and a closing of the Portuguese garrison. The new climate in Lisbon also demnded a more democratic were held for six seats in a 17-member legislative assembly. In a territory of about 10,000 Portuguese, fewer than 3,000 people voted. The Chinese generally ignored this exercise in Western democracy.

"You can't really blame them for staying out of it," said Jorge Rangel, 32, who was the elected candidate of a moderate faction of young Portuguese that came in second to a more conservative faction. Rangel, who was born here, serves as Macao's director of information and tourism and is an example of the unusually youthful officials working under the 37-year-old Leandro.

Rangel left Macao to study literature and journalism in Portugal, West Germany and Spain, then was drafted and sent to what is now Guinea-Bissiu as an army captain commanding 200 soldiers fighting the African insurgents. He supported the 1974 revolution, which put many other young men like himself in important government posts. But he says, "The way we moved out of the colonies so quickly was wrong. We should have prepared the people first."

Leandro said he wants to prepare Macao for future shifts in the world economy by diversifying industry. While textiles will remain mportant, he plans to encourage "other lines of industry such as porcelain ware, furniture, optical and photographic instruments and electronics." He points out that in just 30 years the the territory was able to turn from a few firecracker plants to a textile industry that exported more than $150 million in goods last year.

Many foreign investors regard the Peking-linked Macao businessmen as intimidating monopolists who make it hard for outsiders.

"But we are bringing a group of American investors in later this year to show them some chances for investment," Rangel said.