Problems with graphs for presentations

When making charts, I notice that there often isn’t a y-intercept line, and the gridlines for the y-axis go underneath the values for the y-axis which is very unusual. Is there a fix to this, if so, how?

Also, when making an area graph, why are the colors for the areas transparent and how could I make them darker and opaque?

For examples of the chart and area graph:

Hello @Keyan_Dehghan, thanks for your question! Yes, the grid lines are just below the value on the axis and I’m afraid it cannot be changed. The idea behind it that the value “stands” on the grid line.
As for your other question - in an area chart, each section is semi-transparent until you hover it with your mouse. Then it becomes darker to better distinguish each section. I guess in your case this difference in color is so visible due to the dark background of your project. If you would make it brighter, the difference when hovering the chart won’t be so visible.