Hi Kansiri,
I’m using 3.30.1 version. I agree with you about some interface changes in different versions, but I think most of the core functions are more or less the same. To make it easier to load dataset or shape file layers, I keep opening the browser panel and layers panel on the left side of the canvas. If they are not visible at the start, I click view, go down to panel and check these two boxes. The other way round is we can right-click on the screen anywhere except the canvas so that we can check the necessary panels and toolbars.