Incorrect amount in Polygon transfer

Hi there,
I use Metamask for years now. But not on the Matic Network.
Three times I transfered USDC on Matic Network, between 2 Metamask accounts, using the “transfer between accounts” functionnality.
3 times it transferred 1/1000000 of the amount: for instance I type “100 USDC”, Metamask shows “-100USDC” but on polygonscan, I see “transfer for 0,000100 USDC”.
What’s the problem and how may I fix it ?
When adding the USDC token the default option is “6 decimals” but I don’t know how to change it and it’s not suppose to multiply amounts by 1000000…
Please HELP !!!

Regards from Bordeaux,