how to modify the font size of the content of tooltip

[PapaMadeleine2022]

hello, I feel the font size of the content of tooltip is small, but I spend much time to find solution but failed, So I made a 'popover'. When I click a span element like:

<span name="explanation" class="explanation-tooltip glyphicon glyphicon-question-sign" data-container="body" data-toggle="popover" data-title="hello!" data-original-title="" title=""></span>

the 'popover' function is normal and it shows 'hello!'. But when mouse hover the above span, the 'tooltip' still shows tip:hello! So how to disable the content of tooltip when I use 'popover' ?
can you give some advises.
looking forward to your reply.