As far as setting goes, it's important to realize that Sonnet 137 takes place essentially in the speaker's mind. He's mentally kicking himself, and lashing out at others, for his love troubles. But, that doesn't mean that his mind doesn't envision several scenes of its own making.
For example, the opening four lines of the sonnet feature a (one-way) conversation, with the speaker yelling at the god of Love. As you’ll see in our discussion of the poem’s "Symbols, Imagery, and Wordplay," we’re not so sure that Shakespeare actually wants us to imagine the speaker as literally talking face-to-face with Love. Instead, we think this is more like the typical way in which humans talk to their gods—through prayers (the divinity is often felt to be present, even if he or she isn’t visible). Thus, in that section of this module, we described the way the speaker talks to Love as an instance of apostrophe, which, in rhetorical terms, means talking to somebody who isn’t there.
In the second quatrain (lines 5-8), the scene changes dramatically. Now, all of a sudden, we are in a "bay" where ships are anchored. Then, in the third quatrain, we change settings again. Now, we are on land, looking at a certain plot of earth and wondering whether it is a private plot or is, instead "the wide world’s common place."
Of course, the settings in quatrains 2 and 3 are metaphorical. All of the setting really is inside the speaker’s mind. Still, in a poem designed to explore a mental thought process, we think that Shakespeare is appropriate in recording the way our minds bounce from idea to idea, and from place to place.