Mobile Not Caching

Hello,

We built a WordPress site for a client of mine they were in the middle of changing their name. The old name is Apex. They decided it was too much trouble and went back to the old name which is Southland so we had to switch out the logo.

The new logo which is Southland shows on desktop BUT the old logo which says Apex is showing on mobile -handheld. I thought it was a caching issue. So I cached out my phone and old logo still there. I went to a friends phone who has never looked for the site before still old logo.

What do we do about this? My client is frustrated with me.

Thanks!
Tammy