Some people become confused about what they should use. “That” and “which” can be confusing at times. You normally use that when you are referring to an object. For example, you can say, “I have a ukulele that is red.” You are going to use “that” because you are referring to an object, which is the ukulele.
Then if you would need to use which, you would say, “I have a red ukulele, which is needed for the competition that I am joining.” The use of “which” is timely because this refers to how the ukulele can be used in a certain situation. If you would remember these things, it will be easier for you to figure out how the sentence should be constructed.
There are specific rules that apply when using the words that and which. If removing the words that follow would alter or change the meaning of the sentence, use "that," Otherwise, which is okay to use. If you use that behind a restrictive clause and which before everything else. That being said, which and that can often be tricky. They are both very similar but can be used for slightly different purposes.
For example, "He said that" cannot be changed to "he said which." That wouldn't make any sense. However, if you say, "cars which are always expensive," you could also say "cars that are always expensive." The words which and that are interchangeable.