On Twitter, you can search for a user's tweets, or you can find a specific term within an account.
Steps
Method 1 of 2: Using Twitter's Advanced Search

Step 1. Go to Twitter
Log in with username (or email) and password.

Step 2. Go to Twitter Advanced Search

Step 3. Enter a username
Write the name of the profile you are interested in (for example wikihow) in the field From these users.

Step 4. Scroll down and click on the Search button

Step 5. Done
You can now see the tweets of your favorite user.
Method 2 of 2: Using a Search Command

Step 1. Go to Twitter
Log in to your account.

Step 2. Write From: username (for example From: wikiHow) in the Twitter search bar, then press Enter.
Step 3. Done
To search for a specific term in a user's profile just add it after the From command: username (for example From: wikiHow Vita).