Also some other islands in the South Atlantic, if memory serves. South Georgia…?
Also from memory:
India annexed Hyderabad in 1950, and also forced a change of sovereignty for the remaining Portuguese (and French?) enclaves within its boundaries in the course of the following ten years or so.
Ethiopia annexed Eritrea in 1962 (subsequent to federation ten years earlier). Not a change of territory as the OP perhaps meant it, but it was the forcible loss of an existing separate government.
Japan claims that in the aftermath of WW2 the USSR forcibly annexed some of the islands to its north (the Russian viewpoint is that this was in compliance with the peace treaty).
India annexed Sikkim in the 1970s.
Kashmir probably belongs somehow in this thread as well.
Tangentially related to the theme of this thread are also the creation of the Malayan Union (1946) and the Federation of Rhodesia and Nyasaland (1953); in both cases the British forced various territories under the UK’s protection to surrender a large part of their separate powers of government, and subordinated them to a new and unpopular central government.