I have a large text in arial unbolded, that i'd like to change to arial bold; but many words are italicized; so when i change all arial font to bold, the italicized words become simply bold, as it should. Is there some way to make all of the text bold while retaining the italics (thus making those words bold italic)?
You've got to choose the "Arial Bold Italic" font, if you've got it, for the words you want to be bold italic. There is no "Italic", "Bold"... etc. styling.
Hope this helps.
Character styles! Create a character style that specifies Bold Italic. Then run a Find on all the italic words and switch them to that character style. Then create a paragraph style that indicates that everything should be Bold and apply that overall (the ones with the character style will retain their italics).
You could also apply the bolding via a Character style, but if everything's to be bold you might prefer to have that as part of the Paragraph Style.
Hope that helps.