Let's fix the unnecessary letters showing on the address section within your QBO account.
Just to verify, did you see these random letters in the Customer information window or when trying to create a transaction?
Let's verify if the browser is causing the random letters to show up on the address section. Log in to QuickBooks in a private browser. Let's follow the recommendation below to resolve this unexpected behavior.
Refresh your browser by clicking the Reload icon or pressing F5 on your keyboard.
If the same thing happens, we can log in to your account through an incognito window. This mode doesn't store cache that's why we recommend using it.
For Google Chrome browser: Ctrl + Shift + N
For Mozilla Firefox browser: Ctrl + Shift + P
For Safari browser: Command + Shift + N
If it works fine, we can clear the cache of your regular browser. This helps remove any browser-related issues and refresh your browser's settings. Aside from that, you can use other compatible browsers in QuickBooks Online. Here are other browsers that you can try on:
Mozilla
Google Chrome
Microsoft Edge
For Safari, make sure to use the latest one.
In case you're looking more resources about managing customer's information, you can check the links below: