Shift+F3 is called direct formatting: it is a manual action (like Ctrl+B for bold) which is blindly applied to the target object. In this case, the object is the paragraph.
You need to learn to use styles, notably the two principal categories: paragraph styles which apply a basic default formatting to the paragraph and character styles which locally override the paragraph base style with other formatting.
In your description, you clearly need a paragraph style for your question/heading with camel case (title case). Then you select word “pcb” and apply to it a character style with upper case or small capitals.
Read the Writer Guide for details and experiment.
Meanwhile, you can do it with direct formatting (gut, caution, this is not a good habit) by selecting the word , Format>Character and selecting the desired attributes.
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