If you’re having trouble changing the look of horizontal lines using the style by element tools, you might find some helpful advice here.
Please first make sure that style by element is activated. To do so, go to the Menu of your Creator website, then go to Design > Style and switch on Style by Element. Afterwards, please try the following if you don’t succeed at clicking the horizontal line with the paint roller.
Using browser zoom
Make the view in your browser window larger by using the built-in browser zoom. With most common browsers, you can enlarge the view of a website by pressing and holding the CTRL button on your keyboard and then pressing the plus button on your keyboard. This will make the horizontal line appear larger and thus easier to click using the paint roller.
Change the style as desired, then press and hold the CTRL key on your keyboard and push the minus button to make everything smaller again.