The basic information contained in a Member’s personal profile (as set up by the webmaster) contains consists only of the Member’s name; username and email address.   A logged-in member will have created their own password which is also accessible (i.e. changeable) through the Profile page.
Editing Personal Profile through the Front End of the Website:  Members can access their personal Profile through the back-end of the website as described on the Website Help – Back-End page.  They can also access the same page through the Front End by clicking on their name in the upper right-hand corner of the page and selecting “Edit my Profile” as below:
The Profile page allows members to change any of the information contained on it or add addional information (including a personal “avatar” or image).
To change a password, click on the button “generate password” (near the bottom of the page) and replace the autogenerated code with a new password – see below:
Once finished updating the page, click on “Update Profile” at the bottom of the page.
For further guidance, try https://en.support.wordpress.com/manage-my-profile/ or numerous other help sites.