WhatsApp is owned by an extremely untrustworthy company (Facebook) that has failed to protect its users from hackers, and has deliberately sold their data to companies who use data to manipulate elections for money, and failed in its duty of care for users.
I will be attempting to persuade my friends and relatives to adopt Matrix, which works the same, but is not controlled by one company. It works on phones and PCs.
On your phone, install the app called Element (or one of the many others). On your PC, try it immediately at app.element.io.
Declaration of interest: I am so enthusiastic about Matrix that I managed to persuade Element to employ me.