Whenever I open Character Viewer, I want the Favorites category selected by default as shown in the image. Instead, I find that even if I selected Favorites in the last session, next time the category selected by default is the first category below the horizontal dividing line below Favorites in the left side bar (the Greek category in the attached image).
Is there a way to make Favorites selected by default? If this is not possible, I want at least the category selected in the last session remains selected in the next session. In fact, that is the behavior for all the categories below the dividing line, but not for the categories above the dividing line. For example, in the attached image, if I close Character Viewer while the Arrows category is selected, next time the same category remains selected, but not for the Frequently Used and Favorites categories.
The macOS version is 10.14.3 (Mojave).
Best Answer
It seems that it has been a while since you have asked this question but I still wanted to respond to it because it had gone unanswered and you or somebody else might still use a solution, even if not perfect, to the problem you described.
I have the same problem with the Character Viewer on my iMac running on High Sierra.
The most practical solution I could find was opening it using the keyboard shortcut ⌃+⌘+space and always leaving / closing the Character Viewer when it is in the compact / pop-up state (see the picture). This helps because, if invoked through its keyboard shortcut, the Character Viewer always opens in the state it was in when it was last closed and focuses on the last used category such as the Favorites. You can click on the icon at the Character Viewer's top right to switch between its compact and expanded states.
If I do the above, the Character Viewer always opens in the compact state and focused on the category I left it with. Because most of the characters I use are in my favorites, it nearly always opens focused on the Favorites or the Frequently Used & the Favorites. Interestingly, I don't have this problem with the Character Viewer on my MacBook running on Catalina. It opens focused on the category wherever I left it in including the expanded state.