Update on 2020/04/19:
It now seems to work normally that is the selected Google search engine is now used when I type a search in the taskbar.
I only did a change of search engines between a few engines and waited for the remark similar to "change saved" to be made when I finally selected Google as my default search engine and then I tested and it now works properly.
I will get back here if it would not work properly but consider my remarks not to be accurate anymore.
I possibly the first time not waited for the change saved to be done so it might not have saved my Google search engine as default because of that.

TO THE DEVELOPER LOUIS:
Could you have for this addon a button that I could add wherever I want through customize. By clicking on it, I could toggle quickly between enable and disable for this addon Bing To Google, as sometimes I want to compare my search results in Google with the results given with Bing.

The current option that I have is to display the addons that I have and click disable for this addon then using bing.com temporarily and then again come back to this addon, then click enable. It takes too much time to do that and a button would solve this matter.

Thanks for this addon.

---Update on 2020/01/25 to Louis:
Many thanks to the developer, now the toggle button allows me to switch this addon off when I want to use bing and check the results I can get with bing. Great job, Louis.