Front page title problem with Yoast SEO and Avada theme

Could anyone help?

A: What title did you enter for the front page?
B: What title is output in the source code of your site?
C: What title does Google show?

Do A and B titles match? If not, please try the suggestions in this article: The SEO title output for the plugin doesn’t work as expected

Do A/B and C titles match? If not, please try the suggestions in this article: Google shows different titles for my site

If the problem remains, please provide your website URL for further investigation.

It shows the right title in both the A, B and C. But in C appears sitename before the title with a colon after.

Example: %%sitename%% : %%title%%

Ultimately Google will, as you have seen, make the final decision on what they show in their search results. You may see a different title for all sorts of reasons. This article on why Google wont show the right page titles tries to explain it.

Due to this being handled on Google’s end, there is little you can do to force Google to display the preferred title. The best advice I can provide, unfortunately, is to try a different title for the front page. This article provides advice on crafting good titles for SEO.