Not easy to edit GWEI when value is a decimal

[ibrahimtaveras00]

Describe the bug

Upon attempting to edit GWEI I see a negative number and am unable to successfully edit that value. The only way I got this to work was to "SELECT ALL" per device and then edit the value

Screenshots

Seen here = https://recordit.co/J7rQH8dlA2

To Reproduce

1. Ensure you have Arbitrum Testnet on your wallet as a custom network
2. Go through the normal send flow to end up on the confirm view
3. While on the confirm view tap to edit the fee and try to change the value

Expected behavior

I should be able to edit GWEI without having to select all

Smartphone (please complete the following information):

• App Version https://github.com/MetaMask/metamask-mobile/pull/2865 and 2.6 release