Hi Ramisqu,Thank you for upgrading to iOS 10! If you are having issues locating your contacts once you save them from the recent call list or any other area on your iPhone, try checking to see which is your primary account used to save your contacts. You can then choose the contact groups you wish to display. Add contact accounts
Besides adding contacts individually, you can:
Use your iCloud contacts: Go to Settings > iCloud, then turn on Contacts.
Import your Facebook Friends: Go to Settings > Facebook, then turn on Contacts in the “Allow These Apps to Use Your Accounts” list. This creates a Facebook group in Contacts.
Add contacts from another account: Go to Settings > Contacts, then tap Add Account.
Access a Microsoft Exchange Global Address List: Go to Settings > Contacts, tap your Exchange account, then turn on Contacts.
Set up an LDAP or CardDAV account to access business or school directories: Go to Settings > Contacts > Add Account > Other. Tap Add LDAP account or Add CardDAV account, then enter the account information.
Sync contacts from your computer: In iTunes on your computer, turn on contact syncing in the device info pane. For information, see iTunes Help.
Import contacts from a SIM card (GSM): Go to Settings > Contacts > Import SIM Contacts.
Import contacts from a vCard: Tap a .vcf attachment in an email or message.
Search a directory. Tap Groups, tap the GAL, CardDAV, or LDAP directory you want to search, then enter your search. To save a person’s info to your contacts, tap Add Contact.
Show or hide a group. Tap Groups, then select the groups you want to see. This button appears only if you have more than one source of contacts.
Update your contacts using Twitter, Facebook, and Sina Weibo. Go to Settings > Twitter, Settings > Facebook, or Settings > Sina Weibo, then tap Update Contacts. This updates contact photos and social media account names in Contacts.
Add contact accounts Use Contacts from within the Phone app
Add a Favorite. Put VIP contacts in your Favorites list for quick dialing. Tap a Contact, then scroll down and tap Add to Favorites. Calls from these contacts bypass Do Not Disturb (see Do Not Disturb).
3D Touch. To quickly view favorite contacts, tap Extras, then press Contacts. See 3D Touch.
Save the number you just dialed. In Phone, tap Keypad, enter a number, then tap the Add button. Tap Create New Contact, or tap Add to Existing Contact, then choose a contact.
Add a recent caller to Contacts. In Phone, tap Recents, then tap the More Info button next to the number. Tap Create New Contact, or tap Add to Existing Contact, then choose a contact.
Automate dialing an extension or passcode. If the number you’re calling requires dialing an extension, iPhone can enter it for you. When editing a contact’s phone number, tap the Symbols button to enter pauses in the dialing sequence. Tap Pause to enter a two-second pause, which is represented by a comma. Tap Wait to stop dialing until you tap Dial again, which is represented by a semicolon.
Use Contacts from within the Phone appThe steps above should assist you with adding contacts, selecting a primary account to save the contacts to, as well as locating the contacts that you've saved. Thanks for using Apple Support Communities to post your question. Have a nice day.