The idiom "four corners of the world" refers to all parts of the world or every corner of the globe. If you are looking to add some variation to your writing or speech, there are several other expressions you could consider using instead. Ideas include "all over the world," "around the globe," "far and wide," "every corner of the earth," and "across the planet." You could also experiment with regional variations, such as "from the Arctic Circle to the equator" or "from the Andes to the Himalayas." Ultimately, the key is to find a turn of phrase that appropriately captures the scope and breadth of the subject or idea you are discussing.