Please take a look at the image below.
As I am writing this, it is September 8. So, the current day AND the selected day are September 8. Thus, there is a light red background on September 8.
Perhaps, though, I want to look at another date to check which events are (or were) on that date. In this case, I click on the date I want. Let's say I wanted to check what happened on September 3. September 3 is now my selected day.
NOTE THAT the light red background has now moved to September 3. September 8 is the general background, i.e., whatever you set in cells color.
To find this design item...
Step 1: After you log in, click on Calendars (brown box below).
The Your Calendars page will open.
Step 2: Choose the calendar you wish to modify (brown box below).
Step 3: Click on Design (brown box below).
Step 4: Scroll down and click on Days and Dates (brown box below).
Step 5: Scroll down until you find the header Selected day highlight.
To modify this design item...
How to change the Selected day highlight
Default: The default depends on the EventOn Theme. At the moment, it is hardcoded to light red as in the image above.
Custom: Click on Custom and then click on the circle to choose your color. I have chosen yellow in the example below.
Click Save at the bottom of the column to save your changes.