Calibri does not contain Chinese characters. When you set your font to Calibri, Microsoft Office automatically choose a Chinese font for Chinese you’ve entered.
In your case, it seems that Excel automatically chose Microsoft Yahei (微软雅黑), while Powerpoint automatically chose STXinwei (华文新魏).
They are both correct behaviors. In Excel, people expect to see more general fonts in sheets, while, in PowerPoint, people expect to see more stylish fonts in presentations.
Though what PowerPoint did is correct, if you do want to change the font in PowerPoint, you have to keep in mind that Calibri does not contain Chinese characters. Therefore, you have to choose another Chinese font for it so that the appearance would change.
I personally recommend Microsoft Yahei (the font Excel uses) and STZhongsong (a very bold serif font suitable for presentation titles).