Welcome message is shown in the top right of the header that includes the customer’s name when they logged in. However, with visitors who do not log in your store, a message “Default welcome msg” will be displayed automatically by default Magento 2; and it is impossible to change this default message. Hence, you should make sure that this welcome message have to be more attractive and eye-catching.
Magento 2 configuration allows modifying the welcome message easily by following the guides:
Stores > Settings > Configuration.
On the Admin sidebar, go
Content > Design > Configuration > Select your current theme > .
Headersection. Then, enter the
Welcome Textthat you want to appear.
Cache Managementlink at the top of the workspace. Then, follow the instructions to refresh the cache.
Ref: Magento 2 User Guide
It comes to the end of tutorial: How to Change Welcome Message in Magento 2.