Touchpad not working properly

[samdb]

Hello everyone,

I'm very new to linux and switched from windows to linux mint on my notebook very recently. It's great and everything seems to work fine - except the touchpad.
Moving, clicking, scrolling, everything works, but it all seems laggy.
e-g when I scroll pages on firefox there is a slight delay and it's kind of jerky. Or when I scroll in the menu in all applications it's extremely laggy and jumps up and down. But my notebook also has a touchscreen and when I scroll in firefox or in all applications with my finger, it's smooth without any delay.

It responds in a funny way sometime, when I touch-click something, the cursor jumps a few millimeters to a few centimeters which makes me click the wrong things sometime and that's very annoying.

Also sometimes when I put my notebook back from sleep, the touchpad doesn't work anymore. Can't move the cursor can't click. But I still can work with the touchscreen. I restart the notebook and the touchpad still doesn't work. I can restart it as often as I want but it won't work. ONLY when I put the notebook to sleep and wake it up again, the touchpad miraculously works again.

EDIT: And I've noticed I'm not able to zoom in with the touchpad as well as on the touchscreen.

Does anyone have an idea what the problem is respectively how to solve it?

My specs:

System: Kernel: 4.15.0-42-generic x86_64 bits: 64 gcc: 7.3.0
Desktop: Cinnamon 3.8.9 (Gtk 3.22.30-1ubuntu1) dm: lightdm Distro: Linux Mint 19 Tara
Machine: Device: laptop System: LENOVO product: 2191 v: Lenovo IdeaPad Yoga 13 serial: N/A
Mobo: LENOVO model: INVALID v: 31900003WIN8 STD MLT serial: N/A
UEFI: LENOVO v: 66CN55WW date: 02/28/2013
Chassis: type: 10 v: Lenovo IdeaPad Yoga 13 serial: N/A
Battery BAT1: charge: 42.5 Wh 100.0% condition: 42.5/49.3 Wh (86%) volts: 16.2/14.8
model: Lenovo IdeaPad Mocca2 serial: <filter>status: Full
CPU: Dual core Intel Core i3-3217U (-MT-MCP-) arch: Ivy Bridge rev.9 cache: 3072 KB
flags: (lm nx sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx) bmips: 7183
clock speeds: min/max: 800/1800 MHz 1: 1796 MHz 2: 1796 MHz 3: 1795 MHz 4: 1796 MHz
Graphics: Card: Intel 3rd Gen Core processor Graphics Controller bus-ID: 00:02.0 chip-ID: 8086:0166
Display Server: x11 (X.Org 1.19.6 ) drivers: modesetting (unloaded: fbdev,vesa)
Resolution: 1600x900@59.99hz
OpenGL: renderer: Mesa DRI Intel Ivybridge Mobile
version: 4.2 Mesa 18.0.5 (compat-v: 3.0) Direct Render: Yes
Audio: Card Intel 7 Series/C216 Family High Def. Audio Controller
driver: snd_hda_intel bus-ID: 00:1b.0 chip-ID: 8086:1e20
Sound: Advanced Linux Sound Architecture v: k4.15.0-42-generic
Network: Card: Realtek RTL8723AU 802.11n WLAN Adapter usb-ID: 001-004 chip-ID: 0bda:1724
IF: null-if-id state: N/A mac: N/A
Drives: HDD Total Size: 128.0GB (22.0% used)
ID-1: /dev/sda model: SAMSUNG_MZMTD128 size: 128.0GB serial: <filter>
Partition: ID-1: / size: 117G used: 27G (24%) fs: ext4 dev: /dev/sda2
RAID: System: supported: N/A
No RAID devices: /proc/mdstat, md_mod kernel module present
Unused Devices: none
Sensors: System Temperatures: cpu: 59.0C mobo: N/A
Fan Speeds (in rpm): cpu: N/A
Repos: Active apt sources in file: /etc/apt/sources.list.d/official-package-repositories.list
deb http: //packages.linuxmint.com tara main upstream import backport #id:linuxmint_main
deb http: //archive.ubuntu.com/ubuntu bionic main restricted universe multiverse
deb http: //archive.ubuntu.com/ubuntu bionic-updates main restricted universe multiverse
deb http: //archive.ubuntu.com/ubuntu bionic-backports main restricted universe multiverse
deb http: //security.ubuntu.com/ubuntu/ bionic-security main restricted universe multiverse
deb http: //archive.canonical.com/ubuntu/ bionic partner
Active apt sources in file: /etc/apt/sources.list.d/spotify.list
deb http: //repository.spotify.com stable non-free
Info: Processes: 209 Uptime: 17 min Memory: 1507.4/3823.3MB
Init: systemd v: 237 runlevel: 5 Gcc sys: 7.3.0 Client: Unknown python3.6 client inxi: 2.3.56