Rulebooks are complicated, especially for a game like Starfinder where there's a ton of different elements that all have to come together so you can play your characters. Sometimes, the rules as they're written don't work out as the developers intended. That's where updates come in. The folks over at Paizo have updated the Starfinder core book. Be sure to check out the new changes.
From the post:
For those who missed it earlier this week, we have updated the Starfinder FAQ and Errata with errata for the 1st and 2nd printings of the Starfinder Core Rulebook! You can see these errata in full by expanding their dropdown, and they are also fully searchable using the search bar at the top of the page.
These changes exist largely to clarify intent, fix known issues, resolve inconsistencies, and generally improve quality of life for GMs and other players. Some highlights for player characters include cheaper grenades, medicinals, and poisons, while GMs now have guidance on creating gunnery numbers for NPC starships (and better balanced gunnery numbers for many of the sample starships included). Of course, there are a lot of changes to peruse, and we always welcome more questions, comments, and feedback on our Rules Questions forum.
Also note that the changes listed for the 1st and 2nd printings are already incorporated into both the Starfinder Core Rulebook Pocket Edition and the 3rd printing of the Starfinder Core Rulebook. Eagle-eyed readers of these new printings will notice that we also took the opportunity to clean up stray typos and make language more consistent.