In order to reset the app's login password one has to already be logged in to the app, then go to the app's Settings > Edit User. The database that stores the records is encrypted and password protected using the app's login password; therefore, one must first be logged in to the app prior to changing the password.

If one has forgotten the login password, there are two ways that one can retrieve their forgotten password. The first is to answer the security questions correctly; these questions should have previously been set up, either when creating your user account or by editing the user account. The answer to the third question is case sensitive, so be sure that your answer uses the same capitalization as when you set up the questions. The second method of retrieving your password is by using a Mac computer (if you don't have a Mac, see if you can access someone else's Mac).

First, some background on where the username and password are stored. The app's login password is saved in a part of the iPhone called the "Keychain" which is a separate, secure part of the iPhone; the Keychain can be synced to iCloud and then viewed by using the Mac software called "Keychain Access" as described in the next paragraph. (The password cannot be viewed in the iPhone's Keychain nor in iCloud Passwords for Windows computers; only passwords for websites can be viewed in the iPhone's Keychain or iCloud Passwords, but it can be viewed in the Mac's Keychain Access app, after syncing with your iCloud account.) The app's password, report's password, username, security question answers, your email address, and institution name are all stored in the iPhone's Keychain and are not sent anywhere else other than they are synced to your iCloud account when iCloud Keychain is turned on (for security, they are sent in an encrypted format), so all of those can be viewed on a Mac using Keychain Access.

If you do have a Mac, turn iCloud Keychain on in both your iPhone and your Mac (if it's not already on) by following the instructions in this Apple Support page: https://support.apple.com/en-us/HT204085. Once iCloud Keychain is enabled, then you will be able to see your password using the Keychain Access app, which is in the Mac's Applications > Utilities folder. Once iCloud Keychain is enabled in both your iPhone and on your Mac, open Keychain Access on your Mac and once it's open, search for "Procedure"; you should get several results named "com.rmk-iosapps.Procedure-Log," with each result representing one of the items you entered when creating a user (full name, email, institution name, username, password, and security questions, as well as the report password). Check to see which one represents the login password (the "Account:" field will say "password"), double click on it, then check the "show password" checkbox, enter your Mac's login password and it will display your password; you can do the same to get the username if needed (the "Account:" field will say "username"):

 
(Click on image to enlarge it.)

If you don't have a Mac, see if you can use someone else's Mac, then log in to your iCloud account by going to the Apple Menu > System Preferences... and click on Apple ID. You'll have to sign out of the account of the person who owns the Mac by clicking on "Overview" in the left margin, then click the "Sign Out..." button. Once it's signed out of that person's account, enter your Apple ID then your iCloud password. (The person who owns the Mac should be there to type in their computer's login password to authenticate the change and also to type in their computer's password when you get to the step in Keychain Access where the computer's password is needed.) Once you've logged in to your iCloud account by entering your Apple ID, then make sure that iCloud Keychain is turned on as per the Apple Support link above, then open up Keychain Access as in the previous paragraph. 

The above steps should let you access your password and allow you to log in to the app in the event of a forgotten password.