[Hummingbird] Change WordPress theme issues

Hi there,

Our website is 4 years old. And it's wordpress U-Design theme, which is old too. Due to this reason, we are considering to change to a new wordpress theme such as Avada.

My question is: if we change another theme, will it negatively affect our SERP in google?

I believe lots of website have similar issues. Any sugguestions would be appreciated