I assume you are talking about indents (leading spaces). If so:
- Edit | Convert Indents | To Spaces
- Edit | Convert Indents | To Tabs
For this you need to open such file and select text you want to process.
Alternatively: you can process a bunch of files at once via "Code | Reformat Code..." (will be done accordingly to your Code Style).. but that will do actual full reformat, which may not be desirable in some cases (e.g. limited formatting rules; or rules do not fork as you need (limited options; edge cases); or whatever).