Trying to check if two expressions are equal

So I am trying to check if two expressions are the same. I have seen multiple posts on how we can just put expression 1 == expression 2 and Mathematica returns true or false. This works for a simple example: 3==5 gives false, as it should.

But lately, when I am putting two expressions equal I just get the two expressions as output? They all have the same variables and functions, so how can I make Mathematica understand?

A basic example is putting 3x == x 3, Mathematica will not understand this either. Any ideas on what to do to compare expressions?